Fluid pressure brake



Nov. 26, w, J. c. MQCUNE 22m is FLUID PRESSURE BRAKE Filed July 27, 1938I9 ZIB 2 INVENTOR JOEEF'H C. Mr CUNE ATTORNEY Patented Nov. 26, 1940UNITED STATES lP A'ETJ'" OFFICE i FLUID PRESSURE BRAKE Joseph C. McCune,Edgewood, Pa., assigner to The Westinghouse Air Brake Company,Wilmerding, Pa., a. corporation of Pennsylvania Application July 27,193s, serial No. 221,554

30 Claims.

This invention relates to fluid pressure brakes for vehicles, such asrailway trains, in which the application and release ofthe brakes on thecars of the train is controlled by variations in a train 5. or brakepipe, normally charged with fluid under pressure, extending throughoutall of the cars of the train; and has particular relation to means forincreasing the speed of propagation of a pressure variation through thebrake pipe from 3,0 the head to the rear end of the Vtrain to cause morenearly simultaneous operation of the brakes on the cars throughout thetrain.

' As is well known, in present day conventional fluid pressure brakeequipment for railway trains l operating in either passenger or freightservice, the application and the release of the brakes on the locomotiveand cars of the train is controlled by variations oi pressure in thebrake pipe that extends throughout all the cars of the train, such ,20variations being effected by means of a brake valve located on thelocomotive at the head end of the train. Due to the time required for apressure reduction or a pressure increase initiated in the brake pipe atthe yhead end. of the train to travel through the brake pipe toward t nthe rear end Vof the train, it will be apparent that the operation ofthe brakes on successive cars.

toward the rear end of the train is effected serially. With present dayfluid pressure brake v.23,9 equipment the speed of propagation of thepressure reduction or pressure increase impulse is suiiicientlyv rapidto satisfactorily `control the slack action in the train andpreventundue shock to cars in the train due to the running-in or the 35running-out of train slack resulting `from the initiation of applicationand release of the brakes on dilerent cars at slightly different times.

With the recent trend toward high speed operation of railway trains, newproblems incident .49 to adequate and proper braking of `trains havearisen. One of the primary problems which has arisen in connection withthe operation'of railway trains at speeds of the order of 100 miles perhour in contrast to the more usual present day lower speeds of sixty orseventy miles per hour arises when it is desired to increase the brakingpower to bring a high speed `train to a stop in the same or lessdistance than the usual stopping distance for lower speed trains. Itwill be apparentthat in order to bring a given train to a stop from arelatively high speed inthe same or less stopping distance as from arelatively low speed, higher braking power'must be exerted because ofthe higher kinetic energy of 5)5 the train at the higher speed.

(e1. eos-acc) Aside from the problems incidental to the provision ofbrake equipment for providing increased braking power and withstandingthe increased mechanical and frictio-nal stresses, there is theadditional problem of preventing undesirable slack action in the traindue to the increase of braking power.

It will be apparent that if the braking power exerted on a car oi" atrain is increased, the car will naturally decelerate at acorrespondingly Y greater-rate. Thus, if the rate of propagation of aypressure reduction impulse through the brake pipe is not increased abovethat in present day conventional brake equipment, the run-in of slackinthe train will be more severe due to the '15 greater rate'ofretardation of the cars at the head end of the train on which the.application of the brakes is initiated prior to the application yof thebrakes on successive cars toward the rear end of the train. y l

In order to provide smooth braking action in high speed trains 'of thenon-articulated type it is expedient, therefore, to increase the speedof propagation of a pressure variation impulse through the'brake pipe inorder to decrease the 25 4time lag between the initiation of applicationof the brakes on cars toward the rear end of the ytrain relative to theinitiation of application of vthe brakes on the cars toward the head endof the train. lIn other Words, it is expedient to apply the brakes onall'of. the cars of the train more nearly simultaneously in order toavoid severe running-in of the slack in the train and thus produce thesmooth braking action neces,- sary in passenger trains iorcomfort andeven safety of passengers.

In order to enable' fast time schedules, the operation of railway trainsin high speed service ventails not only the stopping of trainsdistancesequal to or less than present day con- 40 ventional stoppingdistances, as at station stops,

' but alsothe accurate and reliable control of the degree of applicationof the brakes so that the train is not unduly slowed or decreased inspeed vat curves, switches or points of track repair.

Obviously with prompt acting and effective brake equipment, closeregulation of the speed ofthe train can bel effected and, consequently,time may be saved which might otherwise be lost due to the unnecessaryslowing down of the train.

- Another factor which makes it desirable to provide a brake equipmentsuitable for high yspeed train operation is that the track capacity canbe increased and the automatic signal control based upon shorterstopping distances. Ob- 55 equipped for electropneumatic operation.

.viously, with shorter stopping distances, the

taneous application of the brakes and release of Athe brakes on all thecars whereby smooth braking operation and other advantages aboveindicated may be obtained.

In the case of existing passenger cars, such electropneumatic equipmentis notk a practical expedient for the. reason that electropneumaticequipment necessitates all cars of the train beingl The practicaldifficulties involvedif the brake equipment on existing cars were to bemodiiied or converted into an electropneumatic train wire type-of. brakeequipment should be readily apparent, for the reason that conversion of;the brake equipment cannot be effected except over a long period of timeand consequently, it would be impossible to secure or makeup a train inwhich all cars would be equipped with electropneumaticbrake equipment.

, It is accordingly desirable toprovide means for increasing the speed of propagation of a brake control impulse serially through the cars ofatrain Without necessitating that all cars in a train be equippedwithaccelerating means.

' Myinvention accordingly contemplatesthe. pro-- vision of equipmentforindividualr cars includ r ing -a valve mechanism at each vend of thecar associated, as by hydraulic connection, so. as to operatesubstantially simultaneously to produce substantially simultaneously atboth ends of the car a pressure variation in the brake pipek infresponseto a pressure variation traveling through they brake pipe and rstreaching either end of the car. Such equipment on cars providedtherewith'accelerates the propagation of' apres.- lsure variationthrough the .brake pipe at a 'faster rate thaniis possible inthe case ofconf.

ventional present da-y brake equipment and the,

maximum gain in respect to increased speed ofpropagation of a pressurevariation through the brake pipe is obtained when all cars. of the trainare suitably equipped. However, it is not essential that every-car beequipped with acceleratingfmeehanisn'i. Y n i The operation of'trainsmade up of existing present day passenger cars` for which the provisionof electropneumatic train wire brake equipment impractical 'makes itdesirable also to provide a brake equipment therefor-Which Will effecta. more rapid and simultaneous release of :the brakes on all cars eitherfor a, complete release or'for a graduated release. `My inventionaccordingly further contemplates the addition to existing car brakeequipment ofr accelerating means effective to cause a locall supplyoffluid under pressure tothe brake pipe at both ends of the carsubstantially instantaneously uponV a pressure increaseV in the brakepipe iirst reaching either end of the car.

With the accelerating equipment self-confined to each car and related.through the brakerpipe from car to car, it is not essential that' all ofthe cars in a train bev equipped with--` acceleratingv equipment. Thus,my'invention is a practical expedient for improving the operation of theing the hose connection between the rear end of onecar and the head endof another car, it is necessary that the accelerating equipment on thecars operate rapidly enough so that the propagation of the brake controlimpulse through the brake pipe is eiected at -a more rapid 'rate thanthe initiating pressure variation in the brake pipe in order to obtainany benefit from the accelerating equipment. My invention accordinglyfurther contemplates the provision of accelerating equipment on the carswhich is so sensitive and v so rapid in operation as to eiect such aresult.

It is accordingly an object of my invention to provide acceleratingmeans applicable to the fluid pressure brake equipment on existing carsfor increasing the speed of propagation of a brake control impulseserially through the train.

Another object of my invention is, toprovide aA brake equipmentgof` thecharacter indicated in the foregoing object and including hydraulictransmission means. .for propagating' a brake control impulse from oneend of the car to the other in response to a pressure variation set upin the brake pipe.

Another object of my invention is to provide an accelerating equipmentapplicable to iiuid pressure brake systems and including valve means ont-he cars for selectively locally reducing brake pipe pressure at aservice rate or at an emergency rate and for locally supplying fluidunder pressure to thebrake pipe in response to an irnpulse hydraulicallytransmitted thereto from a s'm-iliar Valvemeans at the opposite endofthe car, whereby to accelerate the rate of propaga-.- tion of a brakecontrol impulse serially through theA cars of the train and eiiectvmorenearly `simultaneous application and release operation of the brakes onthe cars throughouty the' train.

Anotherobject of myl invention .isV to provide means for acceleratingthe propagation ofe'ach successive step or variation of brake-'pipepres' sure when effecting a graduated'release ofthe Y brakes.A

Another object of my invention is "to provide `accelerating meanseffective to increase the rate of propagation of a pressure variation inthe brake-pipe and` constantly eiectivefor successive incremental stepsof increasein brake pipe pressurein effecting a graduated release of thebrakes andfincluding means for simultaneously supplying fluid underpressure to the brake pipe from separate local sources at both endsv of3; CEil:v

A further object of `my' invention is to provide accelerating meansy forincreasing the rate of propagation oi a pressure variation impulseseri.- ally through the brake pipe and. adapted to auto-v maticallyproduce a succession of spaced pressure variations in the brakefpipe inresponse to and iii-advance of initiating pressure varia-- jtionset upinthe brakepipe; under manual con-.-

trol whereby to increase the rapidity ofapplicar tion andA release ofthe brakes on thev cars. A

Astill'v further object of'my invention is to guard'.` against:undesired application of the brakes!following a release` of the brakesresulting from overchargeof the brake pipein a brake equipment includingpropagation accelerating -eo l means of the character indicated in theforegoing objects.

Y .A still further object of my invention is to provide a brakeequipment having hydraulic transmission means von the cars forpropagating a brake control impulse and including a method and means forpreventing undesired application of the brakes due to expansion of thehydraullic medium resulting from increase of climatic temperature underservice conditions.

The above objects, and other objects of my invention which will be madeapparent hereinafter, are obtained by means of an embodiment of myinvention subsequently to be described and shown in the accompanyingdrawing, wherein Fig. l is a diagrammatic view showing a ccnventionalfluid pressure brake equipment for a railway ca r and the hydraulicpropagating mechanism provided according to my invention associatedtherewith,

Fig. 2 is an enlarged sectional View of the valve y mechanisms provided,according to my invention, at opposite ends of a car respectively, and

Fig. 3 is a sectional view of a device which may be applied to thehydraulic pipes on each car to prevent the development of undesiredpressure in the hydraulic system due to the expansion of the hydraulicmedium incident to temperature change.

DESCRIPTION or EQUIPMENT For simplicity, my invention is illustrated inFig. l in connection with only two cars of a train but it should beunderstood that the equipment described yis provided on each car of atrain. In Fig. l, fluid pressure car brake equipment is shown comprisinga section of the brake pipe II which is connected to the section of abrake pipe on adjacent cars through flexible hose connectors I2, a brakecontrolling valve-device I3 illustrated for simplicity as the familiartriple valve of the graduating release type operatively responsive tovariations of fluid pressure in the brake pipe II and having associatedtherewith in the usual manner an auxiliary reservoir I4, a supplementalreservoir I4a, and a brake cylinder According to my invention, a valvemechanism I6 is provided at'opposite ends of each car respectively, thetwo valve mechanisms on .each car being connected by three hydraulicpipes I1, I8 and I9 and referred to, respectively, hereinafter as theservice pipe, the emergency pipe and the release pipe. There is alsoprovided at both ends of each car a release reservoir I2 which ischarged with fluid under pressure from the brake pipe II past a one-wayor check valve 22, the valve mechanism I6 at each corresponding end ofthe car functioning to control the supply of fluid under pressure fromthe release reservoir to the brake pipe in the manner to be hereinafterdescribed. v

Considering the parts of equipment in greater detail, it4 should beunderstood that the brake pipe II is normally charged to a certainpressure in the usual manner from a main reservoir on a control car,such as the locomotive, under the control of a conventional brake valvedevice, not shown, which is operative in the usual manner to effect adesired amount of reduction in the brake pipe pressure at a service rateor a reduction at an emergency rate.

Each brake controlling valve device I3, only one o-f which is shown, isconnected to the brake pipe through a branch pipe ID and operatively'controlled by variations of pressure in the brake carried in the brakepipe and to vent fluid under pressure from the brake cylinder I toeffect release of the brakes on the cars. Upon a reduction in brake pipepressure at a service rate, the

l valve device I3 is operative to cause fluid under pressure to besupplied from the auxiliary reservoir I4 to the brake cylinder I5 at aservice rate to effect a service application of the brakes, the degreeof the service application depending upon the amount of reduction inbrake pipe pressure.- Upon a reduction of brake pipe pressure at anemergency rate, the valve device I3 is operative `to supply fluid underpressure from the auxiliary reservoir I4 to the brake cylinder I5 at anemergency rate to effect an emergency application of the brakes. Upon anincrease of the pressure in the brake pipe following application ofbrakes, the valve device I3 is effective to increase the pressure in theauxiliary reservoir I4 correspondingly and to vent uid under pressurefromthe brake cylinder I5. At the same time, the supplemental reservoirIlla is connected in the valve device I3 so as to cause shifting of theslide valve mechanism in the valve device to release lap position whenthe increase in brake pipepressure ceases. When pressure in the brakepipe is completely restored to normal value, the slide valve mechanismof valve device I3 remains in its release position in which theauxiliary reservoir and supplemental reservoir are charged to thepressure in the brake pipe.

The valve mechanism I6 is shown, for convenience, in Fig. 2 indiagrammatic extended form but it will be understood that in practicethe casing of thek valve mechanism is suitably sectionalized forassembly and disassembly and the arrangement of the parts is suchas toform a relatively small and compact unit.

Each valve mechanism I6 comprises a service portion, an emergencyportion, and a release portion. Considering these portions of the valvemechanism in the order named, the service portion includes a servicediaphragm 25 suitably clamped along the periphery thereof in the casingso as to form at one side thereof a chamber 26 and at the opposite sidethereof a chamberl21. The chambers 26 and 21 are relatively small beingof the order of possibly 40 or 50 cubic inches for a reason which willbe hereinafter made apparent. With the chambers 26 and 21 charged withfluid at the same pressure from the brake pipe in the manner to behereinafter described, the service diaphragm 25 is positioned in anormal central position due in part to its own inherent resiliency andin part to the o-pposing forces exerted on the diaphragm by two springs28 and 29 located in chambers 26 and 21 respectively. The springs 28 and29 are of such strength that when the differential of the uid pressurein one of the chambers 26 and 21 over the pressure in the other of thechambers exceeds a certain amount, such as three-quarters of a pound persquare inch, the diaphragm is flexed in the direction of the chamberhaving the lower pressure. i

Associated with and adapted to be operated by downward iiexing of thediaphragm 25 is a collapsible type double beat valve device including anupper supply valve 3l and a lower release rvalve 32, a coil spring 33being interposed be:

tween the valves 3| and 32 to urge the valves apart. The supply Valve 3|has a stem .35 fluted adjacent thevalve which extends through a suitablebore connecting the chamber 27 to a chamber 36 containing the valves 3|and 32 to a point in close proximity to a follower disc 37 interposedbetween the lower face of the diaphragm and the -spring 29.

The release valve 32 has a flange formed thereon and a coil'spring 38 isinterposed between the -iiangeand the casing in such manner as tonorfmally unseat the release Valve 32 and kseat the supply valve 3|. Therelease Valve 32, when unseated, establishes communication from the.chamber 36 to a chamber 39 which is constantly connected to atmospherethrough an exhaust po'rt and passage 4 I.

, The chamber 36 is connected through a passage 42 to a chamber 43formed at one side of a diaphragm 44 suitably clamped along theAperiphery thereof in the casing. On the opposite side of the diaphragm44 is formed a chamber 45 which is constantly connected to acorresponding chamber of the valve mechanism |6 at the opposite end ofthe car through the service pipe |7. yThe chamber '45 and the connectingpipe |7 are iilled with a suitable hydraulic medium, such as oil,glycerin or a mixture of water and an antifreeze substance, in a mannerwhich will be hereinafter described.

The diaphragm 44 has secured thereto a stem 46 which extends inclose-fitting relation through a bore formed in a wall between thechamber 43 Aand another chamber 47. A valve 46 ofthe poppet type iscontained in a chamber 49 which is constantly connected to and chargedwith uid under pressure from the brake pipeV through a branch passage 5|and a branch pipe and passage 52. The valve 48 has a uted stem which'extends into the chamber 47 and contacts the end of the stem 46 of thediaphragm 44. A coil spring A 54 interposed between the valve 46 and thecasing andthe chamber 47.

yieldingly urges the valve 48 to a seated position closing communicationbetween `the chamber 49 The stem 46 of the diaphragm 44 is of suchlength as to normally insure seating of the valve 48, but is effectiveto engage the utedstem of the valve 48 and unseat the Avalve 48 inresponse to pressure transmitted hydraulically through the pipe |7 andeffective in the chamber 45 on the lower face of Athe diaphragm 44.

Itwill be apparent that when the service diaphragm 25 flexes downwardly,the follower plate 37 engages the end of the stem 35 of the supply valve'3| to effect unseating of the valve 3| land the seating of the releaseValve 32. With chamber 27 .beneath the service diaphragm 25 charged withfluid under pressure from the brake pipe in a manner to be hereinafterdescribed, it will thus be seen that uid under pressure is supplied pastthe supply valve 3| and through the passage 42 to the chamber 43 abovethe diaphragm 44, thus exerting a force on the diaphragm to cause apressure impulse to be transmitted hydrauli-cally tothe chamber 45 atthe lower side of the diaphragm 44 of the valve mechanism E6 at the`opposite end of the' car. r

Chamber 36 is also connected through a passage 56 to a so-called quickservice chamber 57. Passage 56 contains a restriction or choke 58, yfor`controlling the rate of supply of iuid under pressure to the quickservice ychamber 57, and a voneway or check valve 59 of the ball typefor .preventing .'back-'iiow of uid under pressure .through the2,223,113' passage 56 to the chamber 36 for a reasonwhich will be madeapparent hereinafter.

A second quick service chamber`6| is connected serially to the firstquick chamber 57 .through a restricted passage or choke 62 and is opento atmosphere through a restricted passage or choke 63'for a reasonwhich will also be made apparent hereinafter. f

Chamber 47 is connected to the passage 56, at a point between the choke56 and check valve 56, by a branch passage 65.A It will thus be seenthat when the supply valve 3| is unseated by the downward flexing of theservice diaphragm 25, uid

under pressure is vented from chamber 27 and,

as will be seen hereinafter, from the brake pipe through the passage 56to the quick service chambers 57 and 6|. It will also vbe seen 'thatwhen the valve 46 is unseated due tothe upward -flexing of the diaphragm44, rfluid under pressure,A is vented from the brake pipe to the quicklservice chambers 57 and 6|. In either case, due to the close t ofthestem 46 of the diaphragm 44, the iluid pressurein the chamber 47 isnot effective in chamber 43 on the upper face of the diaphragm 44. Thusthe pressure impulse transmitted hydraulically to the chamber 45 beneaththe diaphragm 44 is not nullied by the pressure of the huid flowing pastthe Valve 48.

Associated with and operatively controlled by the pressure in the quickservice chamber 6| is a suppression valve device comprising a valvepiston 66 and a collapsible type double beat valve having an uppersupply valve'67 and a lower release valve 68. Valve piston 66 operatesin a suitable bore formed in the casing andrhas an annular gasket itaining the valve piston 66 opposite to the annular rib seat 78 is anannular gasket 72, on which the valve piston 66 is adapted to seat whenshifted upwardly away from ,the annular rib seat 76, to

prevent leakage of fluid under pressure past the valve Ypiston to theback side thereof. Loosely contained in a recess 73 formed on the backside `of the valve piston 66 is a piston 74 'having a Fluted stem 75which projects through a suitable opening in the casing wall at theupper end vof the bore containing the valve piston 66 into a chamber 76Where it engages the lower end of the iiuted stem of the release valve68'which also projects into the chamber 76. Interposed in the recess 73between the back side of the piston and the piston 74 is a coil spring77 which yieldingly permits relative movement of the valve piston 66 andthe piston 74 toward each other. Interposed between the casing wall, atthe upper end of the bore containing the Valve piston 66, andthe piston74isanother coil spring 78 whichis normally through a passage 8|containing a restriction orv choke 82, the purpose of which will besubsequently made apparent. The space in the bore at the outer seatedarea of the valve piston 66 is connected through a branch passage 83 tothe passage 8| at a point between the chamber 76 and the choke 82.A

Interposed between the valves 61 and 68 is a coil `spring 84 whichyieldingly permits movement of the valves toward each other. The supplyvalve 61 has a flange thereon; and a coil spring interposed between theflange and the casing wall of the chamber 86 vcontaining the valves 61and 68 normally urges the valves 61 and 68 downr wardly into unseatedand seated positions, respectively.

Associated with and controlled by the valves 61 and 68 is a pressureequalizing valve 88 of the diaphragm type hereinafter designated thediaphragm valve. Formed at one side of the diaphragm valve 88 is achamber 9| which is nor-` mally subject to the pressure in the chamber21 at the lower side of the service diaphragm 25 through a passage 92 inwhich is formed a chamber 93. At the opposite side of the diaphragmvalve 88 is formed a chamber 94 which is constantly connected by apassage 95 to the chamber 86 containing the valves 61 and 6B.

The fluted stem of the supply valve 61 extends through a suitableopening connecting the chamber 86 to chamber 93 and thus, with thesupply valve 61 unseated as it normally is, chamber 94 is also chargedto the pressure of the fluid in the chamber 21 at the lower side of theservice diaphragm 25. With the pressure of the fluid in the chambers 9|and 94 on opposite sides of the diaphragm valve 88 equalized, a coilspring 91 interposed between the valve 88 and the casing wall in thechamber 94 urges the diaphragm valve 88 into seated relation on anannular rib seat 98 to close communication between the chamber 9| and apassage 99 leading to the chamber 26 at the upper side of the servicediaphragm 25.

Included in the passage 99 is a chamber |0| containing a one-way orcheck valve |02 of the disc type which is yieldingly urged intov aseated relation on an annular rib seat |03 by a coil spring |04. Thespring |04 is of such strength as to maintain the valve |02 seatedunless the pressure in the chamber 21 at the lower side of the servicediaphragm 25 and effective on the inner seated area of the valve |02through passage 92 and a branch passage exceeds the pressure in thechamber 26 at the upper side of the service diaphragm 25 by a` certainuniform amount. If the pressure in the chamber 21 exceeds the pressurein the chamber 26 by an amount exceeding the strength of spring |04,check valve |02 is unseated and fluid under pressure ows from thechamber 21 to the chamber 26 until the differential of the pressure inthe chambers is reduced sulciently to permit reseating of the valve |02.Check valve |02 thus limits the differential pressure in the chamber 21over that in chamber 26 to prevent the exertion of excessive forces onthe service diaphragm 25 and resulting in possible injury or fracturethereof.

It will be seen that the diaphragm valve 88 is in parallel with thecheck valve |02 and likewise effective when unseated to establishcommunication for the flow of fluid under pressure from the chamber 21beneath the service diaphragm 25 to the chamber 26 above the diaphragm.The function of the diaphragm valve88, however, is different from thecheck valve |02 because it functions to equalize the pressure in thechambers 26 and 21 on opposite sides of the service diaphragm 25 toterminate a quick service reduction of brake pipe pressure as will bemade apparent hereinafter.

lConsidering now the emergency portion of the beneath the emergencysupply of fluid under pressure |6, there is provided a so-calledemergency diaphragm IIO having chambers |I| and |I2 formed on oppositesides thereof. The emergency diaphragm |I0 is indicated as formedintegrally with the service diaphragm 25 in a gasket |I3 adapted to beclamped between different portions of the casing of the Valve mechanism,but it will be understood that the dia-` phragms IIO and 25 may beseparate from each other and from the gasket |I3. Chamber I|2 diaphragmIIO is conbrake pipe II through the the chamber III valve mechanismnected directly to the branch pipe and passage 52 and above theemergency diaphragm |I0 is charged with fluid under pressure from thebrake pipe through a branch passage ||5 of the pipe and passage 52,which passage I5 contains a restriction or choke II6. In parallelrelation to the restriction ||6 is a passage II1 containing arestriction or choke ||8 and a chamber |I9 having a loaded one-way orcheck valve |20 therein.

The check valve |20 is arranged to prevent the therepast from thepassage 52 to the chamber I I I, but isadapted to unseat to permit thereverse now of fluid under pressure from the chamber |I| therepast andthrough the passage II1 at a rate governed by the flow area of the chokeII8. l

It will thus be seen that the rate of charging of the chamber I I isdetermined by the flow area of the choke I I6 whereas the rate ofreduction of the pressure in the chamber III yis determined by thecombined flow areas of the two chokes I I6 and I I8. This arrangementfunctions to in some degree minimize the possibility of overchargingchamber I I I, as will be explained in greater detail hereinafter. l v

The chamber |I| above the emergency diaphragm |I0 is connected to thevchamber 26 abovethe service diaphragm` 25 through a restricted passageor choke |22 and the chamber .I I2 beneath the emergency diaphragm I l0is connected to the chamber 21 beneath the service diaphragm 25 througha relativelyv large passage |23. It will thus be apparent that thearrangement including the chokes |I6 and II8 and the vcheck valve |20also functions to .prevent overcharging of the service chamber 26 aswell as emergency'chamber I||. The choke |22 has a smaller flow areathan the choke II6 so that when the pressure in the brake pipe isreduced at a service ratel a dif.- ferential fluid pressure is producedin the chamber 26 over that in the chamber 21 suflicient to flex servicediaphragm downwardly without sufcient pressure differential betweenchambers rIII and II2 being produced to effect downward flexing of theemergency diaphragm I I0. At the same time the choke |22 is suicientlylarge to prevent the undesired downward flexing of the service diaphragm25 in response to the maximum leakage rate of reduction in brake pipepressure.

Integrally formed on or attached to the casing of the valve mechanism I6within the chamber III is a downwardly projecting stop |28 which is ofsuch length as to prevent upward flexing of the emergency diaphragm I I0out of its normal neutral position. The purpose of the stop |26 is toprevent the undesired flexing of the diaf phragm IIO upon charging ofthe brake pipe or an increase of the pressure therein, because theupward flexing of the diaphragm no useful function.

I I0 serves A|21 which is interposed between the wall of the I ycasingand a follower disc |28, in contact with the lower face of the diaphragm|110, in Ysuch manner as -to urge the diaphragm upwardly linto contactwith the end of the stop |25, which is the normal position of thediaphragm.

Associated with and operated by the emergency diaphragm i l@ is acollapsible type double beat valve device comprising an upper supplyvalve |3| and a lower release valve |32, the valves |3| and |32 beingyieldingly urged apart by a coil,

spring |33. Interposed between a ange on the release valve |32 -and thecasing wall of the chamber |33, in whichthe valves |3|-and |32 arecontained, is a rcoil spring |35 which normally urges the valves |3| and|32 to seated and unseated positions respectively.

With the release valve |32 unseated, the chamber |34 is connected to achamber |35 which is v constantly open to atmosphere through an' eX-haust port and passage |31. 3| has a stem' |38 which Vis uted along aportion thereof adjacent the valve and which exl The supply valve itends through a suitable opening connecting the sure is supplied fromthe diaphragm "chamber,

v ||2 through a passage MI to a chamber |42 manner as service pipe |1.

formed at the upper side of a diaphragm |43 suitably clamped along theperiphery thereof in the casing.

At the opposite side of the diaphragm |183-is a chamber |55 which isconnected through the emergency pipe I3 to thecorresponding chamber ofthe valve mechanism l atthe opposite end of the car. The chambers |45and emergency pipe |8 are lled'with a suitable hydraulic medium, such asoil or glycerin in the same Accordingly, when the diaphragm |43 of thevalve mechanism I5 at one end of the car is subjected to the pressure ofviiuid'at the upper side thereof in the chamber 42 Such pressure ishydraulically transmitted through the emergency pipe i8 to the chamberM5 at the lower side of the diaphragm |133 of the valve mechanism IS atthe opposite end of the car, thereby causing the diaphragm '|23 of thelast mentioned valve mechanism to be flexed upwardly.

The diaphragm |43 has secured thereto a stem M5 which extends throughand ts closely in an opening through a wall of the casing separating thechamber |42 from a chamber |28' which is constantly connected toatmosphere through a passage and port |49. A. 'valve |5| of the poppettype is contained in achamb-er |52 which is constantly connected througha branch passage |53 with the. branch pipe and passage 52 of the brakepipe. Valve I5! has a fluted stem which extends through a suitableopening connecting the chamber |52 and the chamber |138 and isyieldin'gly urged into seated relation .on an associated Valveseatformed on the casing, by a coil spring |55. When the valve |5| isseated, the iiuted stem thereof vis in close proximity to the end of thestem |25 of the diaphragm ma. i

It will thus be seen that when the diaphragm |43 is flexed upwardly,'thestem lll'thereof engages the uted stem of the valve 5| and unseats thevalve |5| so that fluid under pressure is vented from the brake pipe toatmosphere through the exhaust port and passage |45. The valve |5| is ofsuflicient area that it need be unseated only a few thousandths of aninch to cause a Very rapid venting of fluid under pressure from thebrake pipe. Due to the close fit of the stem |56 with the opening in thecasing wall through which it extends, the fluid under pressure releasedtoatmosphere past the valve |5| cannot act on the upper side of thediaphragm |43 to nullify the hydraulic pressure exerted on the lowerside of the diaphragm in chamber |115.A

Considering now the release 'portion vofthe valve mechanism |6, there`is yprovided in a chamber IGI adjacent the chamber 25 above the servicediaphragm 25 a collapsible type double beat valve device vhaving a lowersupply valve |52 and an upper release valve |53 between which valves isinterposed a coil spring |64 rfor yieldingly urging the valves apart.The release kvalve |53 has a flange thereon and 'a coil spring |65interposed between this flange and-.the casingwall normally yieldinglyurges the valves |53 and |62 into unseated andA seated positions withrespect to associated valves seats formed on the casing. v

The supply valve |62 hasa stem |65 which is uted along a portion thereofadjacent the Valve and extends through a suitable opening 'connectingthe chamber |3| and the chamber 25, the stem |53 terminating at a pointin close proximity to a follower plate 31 in contact with the upper sideof the service diaphragm when the service diaphragm 25 is in its normalposition. v v

When the release valve |63 is unseated, it opens the chamber |6| toatmosphere through an exhaust port and passage |63.

It will thus be seen that when the service diaphragm is flexed upwardlyfrom its normal position, the follower disc 31 on the upper'` facethereof engages the Vend ofthe stem |66 of the supply valve |52 andshifts the valves ,|52 and |53 tor unseated and seated positionsrespectively.

It will be evident that since the chamber A21 I beneath the servicediaphragm 25 is in direct unrestricted communication with` the brakepipe while the chamber 25 above the service 'diaphragm 25 is incommunicationwith the brake pipe through the seriesrelated chokes |22and H6 that, upon charging of the brake pipe, a

l`differential pressure will be built up on the service diaphragm 25suiicient4 to cause the service diaphragm 25 tobe flexed upwardly.

Chamber |6| is connected through a passage |1| to the inner seated areaof la piston valve |12 which operates a vent valve |13. The piston valve|12 is provided with annular gaskets |14 and'l15 on opposite facesthereof; and a coil spring |15, interposed between the piston valve |12and the end wall of the bore in whichv the piston valve operates,yieldingly urges thev piston valve |12 upwardly to seat the annular ket|15 seats on annular rib seat |11 formed on the casing wall on theopposite side of the piston. f

The vent valve |13 has a fluted stem |18 which extends through a bore|19 in the casing and engages the lower face of the piston valve |12within the annular gasket |15. The vent valve |13 is contained in achamber |8|; and a coil spring |82 interposed in chamber |8| between thewall of the casing and the vent valve |13 yieldingly urges the ventvalve into seated relation on an annular rib seat |80 within the chamber|8| and surrounding the bore |19, when the piston valve |12 is seated onthe annular rib seat |10.

When the piston valve |12 is unseated from its seat |10 in response tothe pressure fluid supplied through the passage |1|, it establishescommunication between the passage |1| and a passage |84 leading to achamber |85 at the upper side of a diaphragm |86. Chamber |85 isconstantly open to atmosphere through a passage |81 having a restrictionor choke |88 therein, for venting fluid under pressure from chamber |85while at the same time not preventing the build-up of pressure on thediaphragm |86 in chamber |85. On the opposite side of the diaphragm |86is a chamber |89 which is connected through the release pipe I9 with acorresponding chamber of the valve mechanism I6 at the opposite end ofthe car. The chamber |89 and the pipe |9 are filled with a hydraulicmedium just as are the service and emergency pipes |1 and I8.

The pressure of uidsupplied to the chamber flexes the diaphragm |86downwardly and accordingly a pressure impulse is propagatedhydraulically to the chamber |89 of the valve mechanism I6 at theopposite endl of the car to -c-ause the latter diaphragm to'iiexupwardly.

The diaphragm |86 has secured thereto a stem |9| which ts closely in andextends through an opening in the casing wall of the chamber |85 into achamber |92.

A valve |93 of the poppet type is contained in a chamber |94 adjacentthe chamber |92 and is provided with a iiuted stem which extends intothe chamber |92 through a suitable `opening connecting the chambers |92and |94 and is adapted to be engaged by the end of the stem |9| of thediaphragm |86. With the' diaphragm |86 in its normal unflexed position,a coil spring |95 is eiective to yieldingly urge the valve |93 intoseated relation on `an associated valve seat-in which position the endof the stem |9| of the diaphragm is inclose proximity to the end of theuted stem of the valve |93. It will thus be seen that when the diaphragm|86 is flexed upwardly, the stem |9| thereof engages and unseats thevalve |93. i

The vent valve |13 and the valvel |93 are arranged in parallel relationso that either may effect operation of an inshot valvev piston |91effective to control the supply of fluid under pressure from the releasereservoir 2| to the brake The inshot valve piston |91 operates in asuitable bore and is normally yieldingly urged upwardly by a coil spring|98 at the back side thereof into seated relation on an annular rib seat|99 formed on the casing at the upper side of the valve piston. A pipeand lpassage 52a which opens within the annular rib seat |99 isconnected to the branch pipe 52 of the brake pipe The annular space atthe outer seated area of the valve piston |91 is connected through apassage 4and pipe 20| to the release reservoir 2|. A restricted port 202in the valve piston |91 connects the outer seated area of the valve'piston` to a chamber 203 at the back side thereof. A stabilizing chamber204 formed in the casing is constantly connected through a passage 205with the chamber 203 for providing additional volume for the chamber 203and thereby stabilizing the operation of the inshot .valve piston AWhenthe pressure in the chamber203 and connected chamber 204 is suddenlyreduced,'the release reservoir pressure acting on the outer seated areaof the valve piston |91 overcomes the spring |98 and shifts the valvepiston downwardly away from the annular rib seat |99 and into seatedrelation on an annular gasket seat 203 inset in the casing on theopposite side vof the valve piston, thereby preventing leakage of fluidunder pressure past the valve pistony to the chamber 203. f

In order to cause a relatively quick return of the valve piston |91 toseated position on the annular rib seat |99, a valve 201 having a stem208 guided in a central recess in the valve piston |91 is provided toclose the exhaust communication for the chamber 203 when the valvepiston is shifted into seated engagement with the annular gasket seat206. A coil spring 209 interposed between the end of the stem 208 andthe valve piston |91, in the recess containing the stem 208, yieldinglypermits relative movement` of the valve 201 relative to the valve pistonto insure seating of the valve piston on the annular gasket seat 205,

Fluid under pressure is vented from the chamber 203 through a bore 2||out of which opens a passage 2|2 that is connected to the cham-ber |94`and to the chamber |8|. The vent valve |13 which is contained in thechamber |8| is effective when unseated to establish communication fromthe passage 2|2 to a passage 2|3 leading to a volume chamber 2|4, thechamber 2|4 being constantly connected to atmosphere through a passage2|5 having a restriction' or choke 2|1,'the purpose of which will bemade apparent hereinafter.

The valve |93 which is contained in the chamber |94 is effective, whenunseated, to connect the chamber |94 to the chamber |92 which is in turnconnected through a'passage 2|8, includingY a ball check valve 2|9, tothe chamber 264.' The check valve 2|9is arranged to permit flow of fluidunder pressure through the passage 2|8 to the volume chamber 2|4 and toprevent reverse flow of fluid under pressure therepast.

It should thus be apparent that when the vent valve |13 is unseated,iiuid under pressure is vented from thefchamber 203 to the volumechamber 254 to cause operation of thel inshot valve piston |91 and alsothat, when the valve |93 is unseated, fluid under pressure is likewiservented from` the chamber 203 -to the volume chamber 2|!! to effectoperation of the inshot valve piston |91.

The valve 201 `associated withthe valve piston 91 is adapted to seat on*an annular rib seat 22| surrounding the bore 2li when the valve pistonl|91 is shifted downwardly into (engagement with the annular gasket seat206, thus closing the eX- haust communication from the chamber 203.

The size of the restricted port 202 in the valve piston |91 is such withrespect to the combined volume of the chambers 203 and 204 as to permitequalization of the pressures on opposite, sides of the valve piston |91in a limited time which is relatively short, thus causing the valvepiston to be shifted back upwardly into seated position on the annularrib seat |99 to close the connection between the release reservoir 2|and the brake pipe.

In order to prevent pumping of the valve piston |91, that is, a. rapidsuccession of operations of the valve piston |91, there is associatedwith the valve piston another valve piston 223. Valve piston 223 iscontained in a suitable bore in the casing and is adapted to control thesupply of fluid under pressure from the release reservoir 2| and passageand pipe 20| toa passage 224 which is connected to the volume chamber2I4 through the passage 2I5. The valve piston 223 is normally urgeddownwardly into seated relation on an annular rib seat 225 by a coilspring 226 which is interposed between the back side of the valve pistonand a vent valve 221. Vent valve 221 is provided with a uted stem 228which extends through the bore 2| I into the chamber 203 and unseats thevalve 201 associatedwith the valve piston |91. The valve piston 223 hasa restricted port 23| therein through which equalization of pressure onopposite sides of the valve piston is effected.

When the inshot valve piston |91 is shifted downwardly to supply fluidunder pressure from the release reservoir into the brake pipe, the

downward movement of the valve 201 causes unseating of the vent valve221. With the vent valve 221 unseated, the chamber 232 at the back ofthe valve piston 223 is vented through the bore 2| I, passage 2I2 andpast either the vent valve |13 or the valve |93, depending upon which isunseated, to the volume chamber 2 I0. Thus, immediately following theunseating of the inshot valve piston |91, the valve piston 223 islikewise unseated from the annular rib seat 225 to establishcommunication between the passage 20| connected to the release'reservoirand the passage 224 connected to the volume chamber 2|4.

The volume of the volume chamber 2I4 is relatively small in comparisonto the volume of the,

release reservoirl 2| and thus when the valve piston 223 is unseated,the pressure in the chamber 2|4 is almost instantly built up to thepressure in the release reservoir. The pressure 'of the fluid in thechamber 2I4 is effective through the passage 2I3 and bore |19 on thelower inner seated area of the piston valve |12 to oppose the pressureof the fluid supplied through the passage I1I to the opposite face ofthe piston |12. The spring |16 accordingly acts to shift the pistonvalve |12 upwardly backv to seated relation on'the annular rib seat |16.Reseating of the vent valve |13 is thus effected prior to the return ofthe Valve piston |91 into its seated position on Y the annular rib seat|99.

It will accordingly be seen that when the inshot valve piston |91 isunseated as a result of the unseating of the piston valve |12, it isunseated for a certain length of time to supply fluid under pressurefrom the release reservoir to the brake pipe, and thenv reseated. Butsince the vent valve |13 has inthe meantime been reseated, the inshotvalve |91 will not again be unseated until the pressure in the volumechamber 2I4 reduces sufhciently through the choke 2I1 to enable thepressure of the uid supplied through the passage |1| to again operatethe piston valve I 12 to unseat the vent valve I 13. 'I'his operationwill be explained in somewhat greater detail hereinafter but it shouldbe understood at this point that the operation of the release portion ofthe Valve mechanism is such as` to eiect autoof fluid under pressurefrom the brake pipe to the l release reservoir and to prevent reverseiiow past the check valve to the brake pipe. Accordingly as longas thepressure in the release reservoir 2| exceeds the pressure in the brakepipe,there will be no ow of fluid under pressure from the brake pipe tothe release reservoir. As will be hereinafter explained, the releasereservoir 2| is o-f such volume capacity as to remain at a pressureabove that inthe brake pipe until venting of uid under pressure from thebrake cylinder and the consequent release of the brakes is eiected.Thus, during a release operation, the reservoirs 2| are not initially adrain on the brake pipe-and do not impede the rapid build-up of brakepipe.

OPERATION or EQUIPMENT (a) Charging of hydraulic system It has beenpreviously stated that the pipes I1, I8 and I9 and the connectedchambers in the valve mechanisms I6 at opposite ends of the pipes ,e

are filled with a hydraulic medium, such as oil, glycerin, or a mixtureof water and an antifreeze substance. For simplicity, the vmanner `inwhich the pipes I1, I8 and I9 are iilledwith the hydraulicmedium is notshown in the drawing but it will be understood that each of the pipesI1, I8 and I9 are provided with a suitable connection through which thehydraulic medium may be supplied into the pipe and sealed therein.

For example, a detachable lling pipe may be .connected to each of thepipes and arranged to extend to' a point higher than any point in thepipes and associated chambers of the valve mechanisms I6, thus insuringcomplete filling of the pipes and connected chambers.

If desired,

pressure in the the hydraulic medium may be supplied initially underpressure to the pipes I1, I8 and I9 to insure substantially completefilling, the pressure of the hydraulic medium being relaxed toatmospheric pressure before sealing the inlet to the pipes. Suitablevent valves, not shown,'may

be provided at intervals alongv the pipes I1, I8 and I9 and at otherlocations to ,permit the removal of air trapped in the pipes. upon llingthereof.

Since the pipes I1, I8 and I9 and the connected chambers at oppositeends thereof are adapted to be substantially completely lled, therelatively greater coeicient of cubical expansion of the liquid ascompared to that of the metallic material of which the pipesI1, I8 andI9 may be composed may produce undesired pressure in the pipes due tothegreater expansion of the lquidas compared to that of the pipes inresponse to an increase of temperature.

It is preferred, therefore, to heat the hydraulic medium to atemperature considerably in excess of the maximum temperature which itmay attain under service conditions before supplying it into the pipesI1, I8 and I9. Thus, when the hydraulic medium cools to normaltemperature after being sealed in the pipes, a slight degree of partialvacuum may be produced therein. However, since the diaphragms 44, `|43and |86 subject to the pressure at opposite ends of the pipes I1, I8 andI9, respectively, are of identical areas, the atmospheric pressurenormally'maintained in the chambers 43, |42 and |85 above the diaphragmswill exert opposing balanced forces. Consequently, undesired flexing ofthe diaphragms will not occur'. In the event of the expension of theliquid due to the increase of climatic temperature no undesired pressurewill be created in thepipes tending to cause undesired operation of thevalve mechanisms I6,

If desired, each of the pipes I1, I8 and I9 may have connected theretoan expansion device as shown in Fig. 3. As seen in Fig. 3, such vdevicemay comprise a casing having a base portion 24| and a cup-shaped cover242 adapted to be removably secured in sealed relation to the point 24|to provide a chamberl 243. The baseportion 24| is provided with apassage 244 which is connected to the pipes I1, I8 or I9 through abranch pipe 245 and which communicates through a branch passage 246containing a choke elementv 241 with the chamber 243. The passage 244also communicates with chamber 243 through a passage 248 containing acheck valve 249illustrated as of the ball type.

ranged, as shown, to prevent the supply of hydraulic medium from` thepipes I1,` I8 and I9 through the passage 248 to the chamber 243 and topermit the reverse flow of hydraulic medium therepast from the chamber243 to the pipes I1 I8 and I9. Y

The choke element 241 has a restricted passage 25I therein, the iiowarea of which is sufiicient to permit the hydraulic medium in the pipesI1, I8 and I9 to ooze into the chamber 243 in the event that thehydraulic medium expands due to temperature increase. However, therestricted passage 25| is so tiny in ow area that a negligible amount ofhydraulic medium will flow to the chamber 243 from the pipes I1, I8 andI9 when the diaphragms 44, |43 and I 86 are subjected to fluid underpressure. Thus there is provision for accommodating the increased volumeof the hydraulic medium due to expansion without in any way interferingwith the proper functioning of the valve mechanisms I6 in propagatinghydraulically a pressure impulse from one end of the car to the other.Obviously, if there is any air trapped in the chamber 243 above thehydraulic medium therein, it does not interfere with the hydraulicpropagation of a pressure impulse from one valve mechanism I6 to theother at the opposite end of the car: It will be obvious that when thevolume of the hydraulic medium in the pipes I1, I8 and I9 contracts dueto a decrease ofv climatic temperature under service conditions, thehydraulic medium will be returned to the pipes past the check valve 249due to the pressure of the air trapped in the chamber 243 above thehydraulic medium.

-It may be that an expansion device of the character shown in Fig. 3 andjust described may 'not be required in every instance but it is intendedthat such devices be provided to insure against any possible undesireddevelopment of The check valve 249 is arl pressure in the hydraulicpipes I1, I8 and I9 due to expansion of the hydraulic medium resultingfrom an increase in temperature.

It will be apparent that once the pipes I1', I8 and I9.are filled withhydraulic medium as above described, no maintenance or servicing thereofis required since the hydraulic medium `remains sealed within the pipes,barring leakage vfrom or breakage of the pipes. Y

(b) Charging of the fluid pressure system When the brake pipe II isinitially charged in the usual manner under the control of the brakevalve (not shown )at the head end ofthe train, fluid underypressureflows through the branch pipes 52, 52a and 235, past the check valve 22and through pipe 20| to the various release reservoirs 2 I. Fluid underpressure also flows from the brakepipe throughthe branch pipes I8 to thebrake controlling valve devices I3 each of which' is thereby conditionedto charge the associated auxiliary reservoir I4 and supplementalreservoir Ma and connect brake cylinder I5 to atmosphere.

For purposes of the present application it is assumed that the mainreservoir pressure is normally of the order of 125 pounds per squareinch and that feed valve pressure to which the brake pipe isnormallycharged is of the V'order of 110 pounds per square inch.'- Accordingly,the release reservoir 2|, the auxiliary reservoirs I4 and supplementalreservoirs I4a are charged to a normal pressure of 110 pounds pervsquare inch.

Upon the charging of the brake pipe II on each car, fluid under pressureflows also through the branch' pipe 52 to the chambers 21 and II2'beneath the service diaphragm 25 and emergency diaphragm IIUrespectively and also through the passage 92 and past the unseatedV.valve 61 tov the chambers 9| and 94 on opposite emergency diaphragmIIU and thence' through.

the choke |22 to the chamber 26 above the service diaphragm 25. Adifferential pressure urging the emergency diaphragm III) upwardly isaccordingly produced but upward flexing of the diaphragm IIB isprevented by stop |26.

A differential force is also created on `the service diaphragm 25 and itis accordingly flexed upwardly to effect unseating and seating of thevalves |62 and |63 respectively. Due to the unseating of the valve |62,fluid under pressure escapes from the chamber 26 into the passage I1Iand acts on the inner seated area of the piston valve |12. Since, aspreviously stated, the spring |16 is of su'icient strength to resistunseating of the piston valve |12 from the annular rib seat |14 untilthe pressure in the'passage |1I exceeds a pressure such as '70 or '75pounds per square inch, the passage I1I charges up to the pressure inthe chamber 26.

In the event that an excessive differential force flexing the servicediaphragm 25 upwardlyis produced, the check valve |02 unseats and thuslimits the'` degree of differential force to prevent damage to thediaphragm 25.

When the pressure of the. fluid supplied to the chamber 26 and effectivein the passage I1| on the inner seated area of the piston valve |12increases sufficiently, the piston valve is operated downwardly tounseat the vent valve |13. Fluid under pressure is accordingly suppliedfrom the and almost instantly therewith'the valve |93 of the valvemechanism 'I6 at the rear end of thel car is 'also unseated.

.-As .previously explained, the -unseating of either the vent valve `|13or the valve |93 is eiective to vent the chamber'293 Vat the back oftheinshot valve .piston |91. Accordingly, lrelease 'reservoir pressurea'ctingfcn the outer seated area `of vthe insll'ot .valve pistonI91jshifts it ldownwardly into seated engagement on the 'annular 4gasketseat 2.06 and at the same time the valve 291is'sl1ifted to yseatedengagement on the 'annular Vrib Aseat 221|..y '.Th'e unseating v'of theinshot 'valve piston |91 yestablishes 'communication from the vreleasereservoir pipe and passage 20| to thebranch'pipe 52a of 'the brake ipipevbut vsince the pressure in the brake 4Vpipe and 4release 'reservoir kIiis .being built up simultaneously pastthe check valve 22, there is no'ilow of fluid under pressure from the release Yreservoir to the brakeizpipe kat this time. Thus, the operation of the inshot valve piston |91upon initial charging ofthe :ui'd lpressure brake system is withouteiect.

VWhen the valve 2El1associated with the :inshot valve piston |91 isseatedfonk the annular rib' seat 22|, it :is effective to unseatthe ventvalve 221 -associated with thein'shotvalve piston 223 and accordinglythe'chamber T232 at theback .of Ithe valve piston 223 is vented tothe'cham-ber 2I4 in the `.manner previously pointed out` past either L40the ventfvalve |13 or "the valve |93 depending uponk which valve isunseated. The release reservoir pressure acting in passage 29| l`on vtheouter seated "area of the Valve piston 223 vfaccordingly Yshifts the'valvepiston Y223 Vupwardly to unseat it fromthe annularribseat I'225and accordingly thejreleasefreservir passage :22| yis connected to thepassage '224 'leading 'to the volume lchamber 214. As previously stated,the Volume in the chamber `2|4 is relatively small lin Vcomparison tothe volume of `the "release freservoir v2I 'and consequently 'thepressure 1in* the 'chamber 2 I4 is very rapidly built rup to releasereservoir'pressure which in the initialcharging'of the "brake system isequivalent to brakepipe pressure. y The pressure ofthe iluid inthechamber 2|4 accordingly acts'on the inner seated area'of the piston7valve I 12 in fits loweri position Vand opposes the pressure -exertedon the Yupper face 'of the piston .|112 Ywhich is not building upasrapidly as the pressure in the chamber 2|4 .due :to the exhaust of uidunderl Vpressure therefrom through -thepassage I81fand choke |88.Consequently, the spring '|16 becomes yeiective to shift the pistonValve |12 upwardlyinto seated relation .on the annular rib seat |10,thereby effecting reseating'of' the vent 'valve' I 13 of thevalve-mechanism lI6 at-thehead end-of the car. When the piston'valve |12reseatsfon the -annular `rib seat |19, the fluid underpressure-in'the'chamber |85 is :promptly vented Ato fatmosphere throughthe Apassage'-.|`911z=1.nd-choke'|86 due to the very small Volume fofthe chamber 1.85. `Accordingly the pressure onJthe diaphragm f|86 .ofthe valve mech- .anism |"6 at-the head end .of the car ispromptly l75relieved vand consequently `the upward pressure inthe ychamber .|99vbeneath the diaphragm '|86 of :the valve mechanism I6 at the oppositeend of the lcar is `relieved to effect reseating of the valve |93.Subsequent to the reseating of the vent valve |13 and the valve |93, thechamber 203 and vconnected volume chamber 294 become sufciently chargedthrough restricted port 292 in the :inshot valve piston |91 that thespring '|98 returnsthe'inshot Valve-piston I 91 into seated relation onthe annular ribseat |99, thereby closingthe connection between therelease reservoirand the brake pipe.

VWhen the piston 4valve |12 is shifted to its upper seated position` onthe annular rib seat |710, the lower face of thepiston valve is subjectto Vthe :pressure in the Vchamber' 2M over a larger area and thus,`untilthe pressure in the chamber 2I4 reduces sufciently at a rate determinedby thesize of the-'choke 2r|1 in the exhaust passage 2I5, the ,pistonvalve A.|12 will remain in its upper seated position. Consequently nofurther operation ,of "the -inshot valve piston |91 will occur until-theypressure, in the chamber 2I4 reduces to theipoint where the pressure inthe passage ,|1I -can 'again overcome the. combined force of v .the-spring |16 `and the pressure in the chamber 2I4 acting on the lower.'vface of the piston valve l A further description of `the operation ofthe release portionof the valve mechanism will begiveninconnection-witha release of the brakes following a servicevapplication and .subsequently to Ice-described. Y

y'(c) Service application of the brakes Assuming then that the fluidpressure systemf has been initially charged inthe manner justindicatedand that, with the train stopped or in motion, itis desired toeffect a service application ofV the brakes, such application isinitiated in the usual manner by effecting a service rate of reduction`of the pressure in the `brake pipe vunderthe ,control ofthe brakevalve, not shown, .onacontrol ,car or on the locomotive at the headendof-the train. v

When the 'pressure reduction in the brake pipe llLreaches the branchpipe52 leading to the valve mechanism .I6 vat .the head end yof the firstcar, and for purposes ofthe present description the head endof the carwill` be consideredvas at the left end of the drawing in Fig. 1, theservice diaphragm 250i the valve mechanism I6 at the head .end of the-car is flexed downwardly and causes unseating and seating of the valves3| ,and .32 respectively. Upon the unseating of the valve l3i,.,fluidunder pressure is rapidly vented .from Achamber 21 and the connectedbrakev pipe II through passage 42 to the chamber 43 and .exerts avdownward pressureon the diaphragm '4.4. The fluid pressureforce in thechamber 43 is accordingly Ahydraulically propagated instantly throughthe service pipe yI1 to the chamber 45 at the lower Side ofthe diaphragm44 of the valve mechanism IS at 'the rear end of the car. The valve 48associatedwith the latter diaphragm V44 is lthus unseatedand iiuid underpressure vented -therepast from `the vbraise pipe through passages-5|fand 56 to the quick'service chambers *Hand-6I.

In the case of the valve mechanism I6 at the :head-end of the car, theunseating of thefvalve v,3| .also causesffluid under `pressure to bevented Afrom. thebrake pipe and chamber 21 through passajget56 to thequick service chambers 51 and are initially at atmospheric pressure duetothe exhaust therefrom through the exhaust port 63, it` will be seenthat an initial quick service reduction of brake pipe pressure will beeffected instantly at both the head and rear ends ofthe car due to theventing of fluid under pressure into the first quick service chamber 51.j

Due to the connection of the second quick service chamber 6I to thefirst quick service chamber 10 51 through the choke passage 62, the duidunder pressure vented to the quick service chamber 51 flows at arestricted rate into the second quick service chamber 6| to build-up thepressure therein. Thus there is an initial quick service reduction inb-rake pipe pressure at a rapid rate which reduction is continued at alesser rate after the pressure in the first quick service chamber 51 isbuilt up substantially to the pressure in the brake pipe. Due to thequick service local reduction in brake pipe pressure caused by theunseating of the valve 48 of they valve mechanism I6 at the rear end ofa car, the quick service diaphragm of the valve mechanism I6 at the headend of 25 the next succeeding car in the train responds almost instantlyto effect operation of the valves 3| and 32 in the manner previouslydescribed. Thereafter, the quick service impulse is transmittedhydraulically through the service pipes I1 on 30. successive cars, inthe manner described for the first car at the head end of the train.

It will be obvious that since local quick servie reductions in brakepipe pressure are effected almost instantaneously at opposite ends ofthe car, l and since the valve mechanism |6 at the head end of a carresponds very rapidly to the localquick service reduction in brake pipepressure at'the rear of the next preceding car, the service applicationimpulse will be propagated serially through 40 all the cars of thetrain' at a much higher speed than the speed of propagation of theinitial pressure reduction impulse through the brake pipe set up byoperation of the brake valve (not shown). f It will be also apparentthat in the case of the valve mechanism I6 at the rear end of the car,the local quick service reduction in brake pipe pressure effected by theunseating of its valve 48 produces a downward flexing of its servicediaphragm 25 and the consequent operation of the valves 3l and 32 tovent fluid under pressure from the brake pipe through the passage 56past the ball check valve 58 to the quick service chambers 51 and 6I andthrough passage 42 to chamber 43. 55.' The pressure of fluid supplied tochamber 43 exerts a downward force on diaphragm 44 opposing thehydraulic pressure exerted in chamber: 45 beneath the diaphragm andaccordingly valve 48 may be instantly reseated. However, once the localquick service reduction is begun, and the service diaphragm flexeddownwardly to unseat and seat valves 3| and 32, the closing of valve 48is of no consequence because the local quick service reduction iscontinued past valve 3 I-. The rate 55 of local quick lservice reductionof brake pipe pressure is the same whether valves 3| and 48 are singlyor jointly open since it is governed by the size of the choke 58 in thepassage 56 leading to the quick service chamber 51. 70` The pressure inthe second quick service cha ber 6I builds up to a sufficient pressureto unseat the valve piston 66 of the suppression valve device becausethe restricted exhaust port 63 is of insufcient flow area to preventsuch build-up of 75| pressure and thus valve piston 66 will be shiftedupwardly to unseat the valve 68 and seat the valve 61. Exhaust port 63is provided to prevent undesired build-up of pressure in quick servicechamber 6I due to possible leakage of fluid under pressure thereto fromthe brake pipe past valves 5- 3| and 48. Fluid under pressure is thusvented from the chamber 94 beneath the `diaphragm valve 88 to atmospherepast valve 68l and through passage 8| and, accordingly, the pressure inthe chamber 26 above the service diaphragm 25 `act- 1`0` ing through thepassage 99 on the innerseated area of the diaphragm valve 88 as well asthe pressure from the chamber 21 on the outer seated area of thediaphragm valve 88 in the chamber 9| is effective to unseat thediaphragm valve. 15 Rapid equalization of the pressure in the twochambers 26 and 21 results so that the service diaphragm 25 is promptlyreturned to its normal position.

The vvalves 3| and 32 are promptly returned to 20 vseated and unseatedpositions, respectively,` in

response to the return of the service diaphragm 25 to its normalposition and the quick service venting of fluid under pressure from thebrake pipe to the quick service chambers 51 and 6I is 2'5y cut off. Thecheck valve 59 preventsback flow of fluid under pressure from the quickservice chambers 51 and 6I through the passage 56 to the chamber 36 andto `atmosphere past the unseated valve 32. At the same time, with thevalve 32 30 unseated, the fluid under pressure -previously supplied tothe chamber 43 above the diaphragm 44 is vented to atmosphere yandconsequently the uid pressure force previously transmitted hyydraulically through the service pipe I1` to: the 35 lower face of thediaphragm 44 of the valve mechanism I6 at the rear end of the car isremoved. Accordingly, the valve 48 of the valve mechanism I6 at the rearend of the car is immediately reseated, if not already reseated asexplained above, o

to cut off further venting of fluid under pressure from the brake pipetherepast to the quick service chambers 51 and 6I. y vIn the samemanner, when the pressure of the uid in the quick service chambers 6| ofeach 5 valve mechanism I6 increases sufiiciently to shift the valvepiston 66 upwardly, further quick service reduction is cut off.

As long as the diaphragm valve 88 is maintained unseated due to thevalve piston 66 being 50 maintained in its upper position venting thechamber 94 beneath the ydiaphragm valve 88,'no

, further operation of the service diaphragm 25 will result from thecontinued reduction of brake pipe pressure, by the brake valve at thehead ,end 55 of the train being maintained in service applicationposition, because the pressure in chambers 26 and 21 reduces at the samerate.

After a certain predetermined time, however, the pressure of the fluidin the quick service chamber 6I acting on the face of the valve piston66 is vented to atmosphere by Way of the branch passage 83, passage 8|and the choke 82 and thus the valve piston 66 is returned` downwardly toseated position on the annular rib seat 'I0 with the result that valves61 and 68 are returned to unseated and seated positions, respectively,Accordingly, the exhaust of fluid under pressure from the chamber 94beneath the diaphragm valve 88 is cut off and fluid under pres- 70 sureis resupplied to chamber 94 past the valve 61 from the chamber 21 andbrake pipe. Spring 91 thus returns the diaphragm valve 88 intoseatedrelation' on the annular rib seat 98 to close the pressureequalizing communication between the chambersZBrand 21 on opposite sidesof service diaphragm i.'..` i i -1 If-.the .pressure in thev brake pipenow continues to .reduce ata service rate, the service vdiaphragm 5k25is again exed'downwardly to eiect another local quick servicereduction in brake pipe pressure at the head; end of the car. andthepropa; gation'of a pressure impulse through the service pipe |1 tothevalve mechanism I6 at the vrear 105 of the car as previously described.Since'some fluid'funder: pressure may still be retained'in the quickservice chambers 51 and 5I, the second quick service reduction in brakepipe pressure may not be as great as the first.

I 155 Ifitherbrake valve at the head end'of the train is maintained inservice application position sufcientlyflong, a plurality of quickservice reduc-` tions will be propagated serially throughout the trainat successive spaced intervalsof time.l The brakercontrolling valvedevice I3" operates in the conventional manner in response to the localquick service reduction of brake pipe pressure on the corresponding carto cause fluid under pressure to be supplied from the auxiliaryreservoir |14 to the brake-cylinder I5',v the degree .of

pressure established in the brake cylinder corresponding'in eachinstance to the total amount of the reduction in brake pipe pressureresulting Aafter each successive local quick service reduction."Accordingly not only is the application of the brakes on-the differentcars initiated more nearly lsimultaneously but also the build-:up ofpressure. in the brake cylinder is faster than in" r conventional brakeequipment. 3f" It will thus be seen that the operator may graduate theservice application of the brakes 'in the samefmanner as forconventional fluid pressure brakeV equipment and also may effect aservice application ofthe brakes to any desired degree. 40 (d) Releasefollowing ,service application If it isdesired to release the brakesafter a service application, the operator operates -the brake valve atthe head end of thee'train in' the conventional manner from lap positionto release l position andfthen to running position. As is Well known,with the brake valve in release position, fluid under pressure issupplied into the brake pipe'from the main reservoir to rapidly rechargethe brake pipe' and, when the brake valve isin running position, at aslower rate under. the control vof a feed valve which limits theultimate pressure attained in the brake pipe to a pressure lowery thanthat normally carried `in the main reservoir.

The choke |22' in the first valve mechanism I5 reached by the pressureincrease in the brake pipe so restricts the charging of the chamber 26above the service diaphragm 25 thereof as to 6'0 cause a differentialkforce flexing the service diaphragm upwardly due to the more rapidbuild-up of pressure in the chamber 21 beneath the service diaphragm 25.28. is-of such strength as to permit upward nexy ing ofthe servicediaphragm in response to a veryslight differential pressure on thediaphragm 25 such as'three-quarters of a pound per square inch'.v

y past the-unseated valve |62, through chamber I6| As previously stated,the spring The upwardflexing of the diaphragm .25 causesV andpassage-H1" tothe inner seated areaof the pistonvalvefIH- u 4 'i I'Asypreviouslyf stated? the spring |16 isA caf-such strength: as toresisty downward shifting yoi the seated area-of piston valve |12to'shift it downwardly .to unseat the vent valve I 13. Fluid'underpressure' isthus supplied. past the unseated piston valve'i12r from thelpassage I 11| to' theA passageA I8 and chamber |85 and, at the sametime, fluid undervpressure is .vented from chamber 263 at the 2`0fbackcfwthe inshot`v valve piston |91 past vent valve-.|13tof-thevcharnber 2M. The pressure of thefluids supplied to chamber actson vthe diaphragm' Iiand is accordingly transmittedzhydraulicallythrough' the release pipe I9 to the 24.5l chamber A'|8'9loen`eaththediaphragm |86 of the valve;,mecha'nism |62 at the opposite end'of theca'r. to"'caus'ey upward flexing of the latter diaphr'a'gm'fISS andunseating of its associated valve 93. I'h'evunseating of the valve |93eiiects the 3.0:

venting of .Huid under pressure from chamber 253 at the back ofy inshotvalve piston |31A past the `ball/check valve 2.I9 tothe correspondingcha-mber'2lf4.f

' n 'win 'thus be seen than the insnotvalve piston 551 v |91 offvalv'emechanism |15 'at head and rear ends of -a'f car* are practicallysimultaneously shifted downwardly'to connect the release reservoirs 2|associated' respectively therewith to the corresponding'branch pipes52d. and 52 of the brake 40 `The sudden build-up of pressure in thebrake pipe due to the supply of fluid under pressure from the releasereservoirs 2I to the brake pipe produces .almost instantaneous responseof the `piston valve' |12 ofthe valve mechanism I 6 at the hea'dv end ofthe next succeeding" car tovent the chamber 203'at the backof the inshotvalve piston |91 thereof and to transmit a lpressure impulse through therelease pipe |9 to the valve 50.

mechanism at the rear of the car in the manner similarto that previouslydescribed. Y

vItwill thus be seen that the pairs ofv valve mechanisms I6^`onsuccessive cars throughout the train are serially operated-to effectlocal in#` 55 shots 'offluid under pressure into the brake pipe at a.pluralityof-points along the length thereof so that in effect a pressureincrease impulse is propagated' through the brake pipe at a greaterspeed 'than' the ordinary speed oi"A propagation 60 of fa. pressureincrease impulse initiated by the brakev valve at the head end of `thetrain.

Whenthe inshot piston valve |91- shifts downwardly to supply fluid underpressure from the release 'reservoir 2|` to thebrake pipe, the as`- 5sociated Valve 201 seats on-the annular rib seat 225| to' close 01T thecommunication from chamber 203 Ato thef bore 2|;I. The 'combined volumeof the chambers 2|l3`and' 204' is` relatively `small and. consequentlythe chambers are promptly 70 charged 'through the chokey 202l ntheinshotvalvepiston |91,l by uid underpressure suppliedfroml the releasereservoir 2|, toa `suflg cient'degree to enable the spring |98 to`Vshift the-,inshot valve |91 back to seated position on cation betweenthe passage 20| and 224 so that fluid under pressure is supplied rapidlyfrom the release reservoir 2| to the chamber 2|4 to rapidly build-up thepressure therein to the pressure in the release reservoir.

The inner seated area of the piston valve |12 on its lower face issubject to the fluid pressure in' the chamber 2|4 and thus the fluidpressure forces on the piston valve |12 become rapidly sufficientlybalanced to enable the spring |16 to shift the piston valve upwardly andreseat it on the annular rib seat |16 before the inshot `valve piston|91 is returned upwardly into seated relation on its annular rib seat|99. Consequently, when the inshot Valve piston |91 is thereafterreseated on its annular rib seat |39, and the valve 201 associatedtherewith is again unseated to open communication between the chamber203 and the bore 2| the chamber 203 is not immediately again vented.

When the valve 201 is unseated, the vent valve 221 is again seated andaccordingly since the chamber 232 at the back of the valve piston 223 isof relatively small volume and is charged sufliciently through the choke23| in the valve piston 223 in a relatively short time, the spring 226becomes effective to reseat the valve piston 223 to close the connectionbetween the release reservoir 2| and the chamber 2 I4.

When the pressure in the chamber 2|4 reduces sufficiently, the timerequired for such decrease in pressure being determined by the volurneof the chamber 2|4 and the size of the eX- haust choke 2|1, the pressureacting in passage |1| on the upper inner seat-ed area of the pistonvalve |12 again operates the piston valve downwardly to unseat the ventvalve |13 and repeat the operation.

It will be observed that with the piston valve |12 in its upper seatedposition, the chamber above the pressure diaphragm |86 is promptlyvented to atmosphere through the choke |88 and, consequently, due to theremoval of the fluid pressure on the upper face of the diaphragm |86 ofthe valve mechanism at the head end of the car, Vthe hydraulic pressureacting in the chamber |89 beneath the diaphragm |86 of the valvemechanism I6 at the opposite end of the car is ycorrespondingly removedand its valve |93 reseated. It will be observed alsol that the ballcheck valve 2|9 prevents reverse flow of fluid under pressure from thechamber 2|4 through the passage 2|8.

lAs long as the brake valve is in release or running position and thepressure in the brake pipe is thereby being increased, the releaseportion of the valve mechanisms |6 will be serially operated to effect asuccession of local rinshots or pressure increases in the brake pipe atspaced intervals. When the brake valve is returned to lap position, asit is in a graduated release, the service' diaphragm 25 substantiallyinstantaneously returns to its normal position due to the fact thatchamber 26 becomes prompt- 1y charged tofthezpressure in the chamber 21and the brake pipe through choke |22 when the pressure in the brake pipeand .chamber 21 ceases r to increase due tolapping of the vbrake valve.Accordingly, the valves |62 and |63 are returned to seated'and unseatedpositions, respectively,so

Vthat the passage l1| is vented.y .to atmosphere vthrough theexhaustport |68 past the unseated rvalve |63. It will accordingly be seen thatwhen the brake valvel at the head end of the train is lapped, the localinshots into the kbrake pipe cease, :and that the valve mechanisms I6are automatically responsive for each successive increment of increaseof brake pipe pressure in a graduated release operation to effect alocal inshotof fluid underpressure into the brake pipe in advance of thepressure increase impulse initiated at the brake valve.

It should be understood that the release'reservoirs 2| are of suicientcapacity in relation to thevolume of the Ybrake pipe to supply alimitedamount or inshot of fluid under pressure n to the brake pipe locally toincrease the pressure therein, without excessively draining or `reducing the pressure in the release reservoirs.`The relative capacities ofthe release reservoir kand brake pipe' will be discussed hereinafter atfurther length inconnection with the release of the brakes following anemergency application of the brakes.

When the `fluid pressure is increased in th-e brake pipe thebrakecontrolling valve dethat the brakes are completely released. In thecase of a graduated release, in Which the pres sure in the brake pipe isrestored in successive steps or increments ofpressure, the'pressure inthe auxiliary reservoirs will be correspondingly recharged andthepressure in the brake cyline ders correspondingly" reduced to reducethe degree of applicationof the brakes. Obviously, due to the operationofthe release portion of the shots in the brakeipipe, the brake pipewill be restored more rapidly to its normal pressure and consequentlythe release of the brakes will be leffected more rapidly than in thecase of the` conventional fluid pressure brake system. The rapidresponse lofthe brakes enables close regu*- lation of the speed' of thetrain so that unnecessary slow down can be avoided and faster travelingschedules maintained.

In the embodiment of my invention shown,

the release portions of the valve mechanisms I6 Vat opposite ends of acar are associated hydraulically to effect propagation of a brakerelease impulse serially through the train at a greater speed than thepressureincrease impulse initiated by the brake valve. However, I wishto point out that these`release portions are effective to ac celeratethe releasewhenthe hydraulicconnection is not employed, and they couldtherefore i be'incorporated in a conventional fluid pressure brakesystem Vand .when so incorporated would respond tothe pneumatic pressureimpulse, alone and be eflectiveto increase the rate of build-up in thebrakepipe upon release of ythe brakes.

vvalve mechanisms |6 to effect successive local intrims,r if inlinesystem 'here illustrated the re- .lease fpipel on one ormorepf/the carsshould .be broken.` andy thev hydraulic` transmission of an `.impulsefrom one end vof the car .to .the other fail, ,thereleaseportions of thevalve mechanisms .I lneverthelessrespond -to .the pneumatic impulse .in.the brake pipe and-.function to accelerate the .build-up. of pressurein the lbrakepipe ata greater ratethan 'in .conventional fluid pressurebrake equipment,v and accordingly cause a more rapid releaseof .thebrakes throughout the train than Wouid be effected .in the .case vofconventional iiuidpressure brake equipment. .It.should beunderstood,ntherefore, that my .invention :contemplatesthe provision vof.valve mechanisms corresponding tothe release portions ofthe Valvemechanisms I6; withoutany ,hydraulicv connection-between the Valvemechanisms `at opposite ends of the car. It is .deemed unnecessary. toshow i such an. arrangement'A Vin -ar View separate from that of Fig. 1since-.the arrangement will Whenv it is desired toeiTectan-emergencyaploeizrea'dily` .understood from .the .abovevexplanation.,

plicationg'ofyithe brakes, the brake v 'alVe ;at.v the head end ofthetrain is operated to emergency ,ofpressure in the brak-e pipe I I.

.position to Yeffect an emergency rate of reduction Upona reduction ofthel pressure in the brake pipe at an emergency rateA at fthe, headvfnd, Qf the train, the emergency r diaphragm I I of*v thez valvemechlanismd atthehead endof the rst carris urged .downwardlyv tol unseatand seatnthe ,valves I3] ,andl |32, respectively, dueto the difterentialnuid pressure force4 created onthe diaphragm. Fluid .underpressure isaccordingly locally ventedfrom the chamberI/IZ and the connected brakepipe .past the unseatedvalve I3I through chamber I 3ft andl passage -IAISto ,the `chamloer |42 above the v pressurek diaphragm I3. yThe pressureof `the 1 fluid inthe chamber |422 transmitted hydraulicallythroughjtheemergencypipe I8 tothe Aclianri- .bergli ,beneathfthediaphragm U13 ofthev alve mechanismj. at,4 thel opposite end of ,the car, andcauses'thediaphragm tobe correspondingly l.iiexedLupwardly,tounseat itsassociated valve ',I5I. Valve. I5I kis of relatively `Vlarge area.- andconsequently.; requires but ...a Slight, unseatin'e .movement to. .cause.rapid :venting of fluid under .pressurefrom the. brake gripe t0..atmosphre through` branch pipeand passage 52, chamber Il, andthe'exhaustpassage M9. l

. Since the @emergerlydiaphragm I. l0. is flexed ydownwardly in responseto a v er y` slight differential Q,f.pressure in chambersjlll andv IIZ,it willbe:.arparentthat aimee# instantly upon "the operation of thebrake valve'to emergency position, the emergency portion Qflthe Valvemechanisms Iii` at oppositeends of thesfirst car `are joperatedtolocally vent .the brake pipe at a rapid rate and thatthe Valvemechanisms I6 on succeeding cars are serially operated in response tothe local reduction of brake pipe pressure on the preceding car `so thatthe s peed of propagation lof the emergency.reduction through r`thebrake pipe much fastertthan the speed of the pressure reduction .Ainitiated by thek brake val-ve at the v'headend of theitrain; 1 1

It Willibelapparent that as'long 4as the brake y valve attheheadyendi ofthe trainrema-ins in emergency position, the pressure :in thecbrake pipe'continues 'to decrease atgan 'emergency irate and :that .consequently,the emergency. *,po'rtion `of lthej/talve mechanisms I;6 W'illfremainconditioned .to locally `vent -the .brake pipe. As in the conventionaluid'zpressure brake system', each .of the brake controlling valvetdevices I3. on .the .cars operates in response to the emergencyreduction of the brake pipe pressure .torefiect .the supply of fluid.underpressure from the auxiliary .reservoir I4 .to the brake. cylinder...I 5. at anemergencyrate, the :ultimate .pressure established'in thebrake cylinder being .thepresi .sure of equalization rbetween theauxiliary reservoirs .and the corresponding brake cylinders. Ob-

.speed service willbe tolerable due to the more'.T

nearly. simultaneous .application of the brakes on vthe v.carsthroughout the train.

Since. the service portion of each of the valve mechanisms. J6 `respondsto :a service .rate of reduction in `brake .pipe pressure, it alsooperates .in response to an yemergency ,rate of reduction in brake pipepressure. :.Accordingly, `in'an emer- Vgency..applicationiof the brakes,.the service and emergency. portions :function vsimultaneously .tolocally vvent the 'brake vpipe and vpropagate pressure reduction.impulses .hydraulically throughout the train. Thefact Athat :the.service portion of the valve .mechanism 16 responds to the emergencyreduction of .brake pipe `pressure is .unob- J'ectionable .since theoperation Aoi? `the service portion simply aids in reducing the brake`pipe pressureandin hydraulically propagating apressure reductionimpulse'. in the brake pipe.

Invi'eWof the 'fact .that'the fluid under pressure `in the brake pipeI;Ir iseventually completely vented to atmosphere .in an emergencyapplica- -tion of the.brakes,...it will be .seen that ultimately the-iuid .underpressure .in .the .chambers II I and I I 2 on opposite sidesof the. emergency diaphragm I I0 and in the chambers 265 and 2I onftheopposite sides of the service .diaphragm 25 will be Vented -to.atmosphere .and the diaphragms respectively returned to .theifnormalorneutral positions thereof. Upon the return' offthe emergency:diaphragm I Irlll to its normal position, the Valves -I3I and |32 are*respectively seated and unseated and conselquentlyvthe fluid-underpressure in the chamber 'I2 Aaloove'the pressure diaphragm -I-43 of the`valve mechanism lI6 Aat the head end of a lcar is released throughtheatmospheric exhaust port |37 past'theunseated valve |32,therebyrelieving rthe pressurein the chamber M at the'lower side of thepressure 'diaphragm M3 of the Vvalve mechanism I6 at theopposite endofthe car and causing valve I5! .associated with the latter diaphragm`M3A tobe reseated. In asimilar manner valves 3 I vand v32 associatedwith the service diaphragm are. returned to seated and unseatedpositions :and ventingiof-,uid under pressure from (f) Release followingemergency application To effect release of the brakes f ollowinganemergency'application ofthe brakes, the`u`s`ual brake valve, not shown,is loperated. in the con'- ventional manner from emergency position. tore-v lease position to initially charge the brake pipe at a rapid ratedirectly from lthe' main reservoir and Ythen to running position tofurther charge the brake'pipe to its normal pressure 'at a slower rateunder the'control of the feed'valve. Since the mainlreservoir is chargednormally tofa much higher pressure than the normal pressure the brakepipe,it is necessary that the brake valve be shifted to running'positionin order to prevent overcharge of the brake pipe and the consequentundesired reapplication of the brakes.

Since the auxiliary reservoir pressure reduces during an emergencyapplication of the brakes to the pressure of equalization with the brakecylinder, the pressurein the brake pipe mustrst be restored to 4apressure higher than such pressure in order to cause operation of thebrake controlling valve devices I3 to release position to initiatetherelease of fluid under pressure from the brake cylinder and theconsequent'release of the brakes following an emergency application ofthe brakes. The pressure to which auxiliary pressure may be reducedduring an applicationof the brakes under the assumed conditions may beof the order of fifty or sixty pounds per square inch.

With the brake valve in release position sup-v plying uid under pressurefrom the mainreservoir at a rapid rate into the brake pipe, suchpressure is rapidly attained in the vbrake pipe and accordingly thebrake controlling/valve devices are rapidly serially operated inresponse to the increase in pressurein the brake pipe to releaseposition'to initiate the release 'of the brakes on the cars. With thebrake valve in running'position causing charging of the brake pipe underthe control of the feed valve, the restoration of `the pressure in thebrake pipe to its normal pressure is at Ia relatively slow lrate andthus in conventional fluid Apressure brake equipments considerable timeis consumed in completely releasing the brakes following an emergencyapplication thereof. In my invention,` the release portion of each ofthe valve mechanisms I6 operates as in the case of a release of thebrakes following a service application when they pressure inthe brakepipe is restored suiiiciently to unseat the piston valve |'l'2 to causea succession ofvlocal inshots into the brake pipe to increase the rateof bulld-upof pres.- sure in the brake pipe to a rate comparable totherapid rate of recharge withthev brake valve in release position.

It will be apparentI that during a service or emergency application ofthe brakes the release reservoirs 2| remain charged to the normalpressure carried inA the brake pipe and, as assumed previously, suchpressure may be. of the order 'of 110 pounds per square inch.Furthermore, as previously stated in'connection'with the release of thebrakes following a service application, the capacity of the releasereservoirs 2| is sumciently large in relation to the volume of the brakepipe that the reduction of the pressure in the release.

reservoirs dueto the local supply therefromto the brake pipe duringtherelease operation'is only a small percentage of the normalpressure. Forexample, if the lrelease reservoirs are normally charged to a pressurelof 110 pounds per square inch, a reduction to :only 1,03l pourielsyperisquare in'o'h'pressure 'may result due to the local supply therefromto the brake pipe during the release operation.` o

'It will thus be apparent that during the initiation of the release ofthe brakesfollowing an emergency application and for the major portionof the interval during which the brake pipe is being charged with udunder pressure, the releasejreservoirs 2| higher than that. in the brakepipe and consequentlyno fluid under pressure is supplied thereto pastthe check valves 22. Thus, until the fluid under pressure issubstantially completely vented from the brake cylinder, the releasereservoirs 2| do not constitute a drain on the brake pipe andconsequently do not in any way impede orrender sluggish the propagationof a pressure increase impulse through the brake pipe to initiaterelease of the brakes, or impede or render sluggish the continuedrelease of fluid under pressure from the brake cylinder.

When. the pressure in the brake pipe is rev stored to a degree higherthan the reduced presare charged to a pressurev sure brake Iequipmentfor releasing the brakes is saved due to the continued rapid release offluid under pressure from the brake cylinder throughout the releaseoperation. p

. 1t will -be apparent that since a fluid pressure of atleast '75 poundsper square inch is required to unseat piston valve |12 of the valvemechanisms ||i,4local inshots into the brake pipe do not begin untilsuch time as it is required in order to maintain the rapid rate ofbuild-up in the lbrake pipe after the brake valve is shifted torunningposition from release position.

In conventional fluid pressure brake equipmentthe rapid in-rush of fluidunder pressure from themain reservoir into the brake pipe at the head,end of the train with the brake valve inf release position temporarilybuilds-up the pressure in the brake pipe at the head end of the `trainto a ldegree in excess of the normal pressure in the brake pipe, whichpressure reduces automatically, that is runs away, due to theilow offluid under pressure towardthe rear end of Ithetrain in the brake pipewhen the brake Valve is shifted to running position.

Accordingly, in order to prevent overcharging of the diaphragm chambers26 and above the service diaphragm 25 and `emergency diaphragm |0 of thevalve mechanism IB, the oneway check valves |20 are provided in thechargingccmmunication for these chambers to restrict the charging of thechambers to a rate determined bythe ow area of the choke ||6 alone.Furthermore,=durng the release of the brakes following either a serviceor an emergency application the upward flexing of the service diaphragm25 to unseat and seat the valves |63 and |62, respectively, connects thepassage to the chamber 26 above the service diaphragm 25 and thus tosome extent enlarges its volume to mitigate the effect of overcharging.In addition, when the pistonyalve |12 is unseated, the chamber 26 is;connected through the passage |84 to the "fthe choke ist atintervals andconsequently any overcharge occurring therein is dissipated. l Thechambers 26 and Hl are lof relatively smal-1 size, such as 4010i 50cubic inches in order to enable dissipation of the overcharge by the`relatively jrs small choke 188. Y

It is.V desirable to avoid excessive dissipation or diminution of thevpressure in the chambers 26 `and Hl by'vvay` of the choke |38 and,accordingly, the spring' tot .for loading thecheck valve H12 isr soselected that when differential pressure on the diaphragms 25 and H0exceeds al certain value, the check valve acts to supply fluid underpressure therepast to the chambers 25 and III.

SUMMARY summarizing, it will be seen that I havedisclosed a iiuidpressure operatedv railway train brake equipment of the type in whichthe brakes are controlled by variations of pressure in a brake pipeextending throughout the train and characterized, according to myinvention, by accelerati-ngmeans for increasing the speed of operationof thel brakes and also effecting more nearly simultaneousy applicationof the brakes on the cars throughout the train as compared toconventional fluid pressure brake equipment.

In the embodiment shown, a pair of valvemechanisms are provided for'each car located respectively at opposite ends of the car andassociatively connected Vby hydraulic connecting means so as to operatesubstantially simultaneously'in response to variations of pressure inIthe brake pipe initiated in the conventional manner by a brake valve atthe head end of the train.'`

The valvevmechanisms operate selectively in response lto service andemergency rates of reduction of pressure in the brake pipe to locallyvent uid under pressure from the brake pipe at a service rate or at anemergency rate, and in `response to recharging ofthe brake pipe toeffect local inshots of iiuid under pressure into the brake pipe.anisms' cn one car is effective to vary the pressure in the brake pipeto cause operation ofthe valve mechanisms on the next succeeding car.

the train are thus serially operated and a brake control impulsepropagated throughout' the train at a much faster rate than is possiblein conventional fluid pressure brake equipment.

Each of the 'valve mechanisms provided according to my inventionembodies a service portion, an emergency portion and a release portion.The service portion is operative automatically in 'response to a servicerate of reduction'of brake pipe pressure to effect a succession oflocalquick service reductions in brake pipe pressure `as long as the brakevalve at the head end? of the train is in service position, the localquickA service reductions ceasing automatically when the-brake valve isshifted to lapA position. vIn an emergency application of the brakes,the emergency portion of the valve mechanisms functions' to effect alocal reduction of brake pipe pressure;v at an emergency rate and theservice portions. also. function to effect a successionvv of Theoperation of the valve mech.

The valve mechanisms on succeeding cars throughout emana local quick.service 'reductions inl brake pipe pressure.

:When the brake pipe is recharged to eiect release of "the brakesfollowing 'a service application, 'the 'release 'portions 4of the-valvemechanisms :function automatically to veffect a suc- Acession of localinshots into the brake pipe, the in'sh'ots ceasing 'Whenever the brakevalve at the head end of the train is shifted to lap position.Accordinglyythe valve mechanism are Aelrective to accelerate `thevprepagation cfa release impulse throughout the train yfor eachsuccessive'increment or step in a graduated release ofthe brakes. Duringa release ofv the brakes 'following an emergency application, vtherelease portion of the valve mechanism'becomes eiective to'cause -'localinshots of fluid under pressure into the 'brake pipe after the brakejpipe pressure has been restored sufficiently to initiate the release ofViiuid under pressurefrom theV brake cylinder, thereby maintaining ltherapid rate of build-up in the brake pipe and' accelerating the releaseof the brakes. I The. valve mechanisms provided according to myvinvention are ofv such nature as to guard against undesiredapplications of. the /brakes'following 'therelease ofl the brakesl duetomovercharging of' the brake'fpipe. 'l

In the embodiment shown, the 'valve mecha- 'nisms at. opposite ends ofkeach car are. associated by hydraulic. connecting means. to effectsubstantially simultaneousy loperation thereof but it should beunderstood thaty any other suitable connect'ing, means, mechanical orelectrical,vv may be l provided to cause simultaneous operation of thetwo valve mechanisms. l

In the case of the specific embodiment shown lin which hydraulic pipesconnect the valve mechanisms at opposite ends of the car, the hydraulicmedium is preheated vto `a. temperature in excess o of the maximumservice temperature and then sealedv Within. the pipes,fthus providingroom for expansion ofv t'hehydraulic medium under service conditions. Ifdesired an expansion device applicable to eachv hydraulic pipe may beprovidedg-"ll5 accordingto. my invention, adapted to remove excesshydraulic mediumtfrom the pipe upon expansion ofimedium dueto. increasein service tem- .peratures and. tok automatically restoreV hydraulicmedium, to the pipe upon vreduction of service l temperatures, VWithoutin any Way interfering with the propagation of brake control impulsesfrom the valve mechanism at one end of the car to the valve mechanism atthe other end ofthe car. o y

The maximum. acceleration of v brake operation y is obtained when thevalve mechanisms provided at opposite ends of. the-car` according to myinvention are associatively connected so as to operatesmultaneouslyindependently of the propagation. of a pressure variation.impulsev through the brake pipe from oneL end of the car. to the other.However, the hydraulic orv lequivalent connections between thevalvemechanisms rmay be omitted' and the valve mechanisms associative; lyvconnected through the'brake pipe only.A In suchcase, the valvemechanisms operate in some measure'to accelerate the propagation ofabrake feo controlirnplulse andI increase the rapidity of op- Y erationof vthel brakes as compared to conventional fluidv pressure brakeequipment' although y not toy the'extent possible4 when associativelyconnected-'independently' ofthe brake pipeas by hydraulic or equivalentconnecting means. c. While my invention has been illustrated'in Havingnow described my invention, what' I claim as new and desire to securebyLetters Pat- 1. In a train brake equipment of the type having a brakepipe normally charged with iiuid under pressure and extending throughall the cars of the train, and brake controlling valve devices on thecars operatively controlled by variations in pressure in the brake pipefor controlling the brakes on the cars; two valve devices for each vcarlocated respectively at opposite ends of the car and` operativelyresponsive to variations of pressure in the brake pipe, meansproviding'three separate hydraulic connections between the two valvedevices, one of the valve devices on each car being operative inresponse to an increase of pressure or a plurality of different rates ofpressure decrease set up in the brake pipe to transmit a pressureimpulse selectively over that one of the hydraulic connectionscorresponding to the type of pressure variation to the other valvedevice to ca-use it to produce a variation in the brake pipecorresponding to that which produced the operation of said one valvedevice whereby the valve devices on successive cars are seriallyoperated to propagate a variation impulse in brake pipe pressure at afaster rate `than the initiating pressure variation. v

2. In a train brake equipment oi the type having a brake pipe normallycharged with iluid under pressure and extending through all the cars ofthe train, and brake controlling valve devices on the cars of the trainoperatively responsive to a reduction of pressure in the brake pipe at aservice rate to effect a service application of the brakes, responsiveto reduction of the pressure in the brake pipe at an emergency rate tceffect an emergencyapplication of the brakes and responsive torestoration of the pressure in the brake to the normal pressurefollowing an application of the brakes for effecting release of thebrakes; two valve devices for each car located respectively at oppositeends of the car, means providing three separate passages constitutinghydraulic connecting means between the two valve devices on each car,one of said valve devices on a car being responsive to a service rate ofreduction of brake pipe pressure to transmit a pressure impulsehydraulically over one of said passages to the other valve device tocause it to operate to effect a reduction of the pressure in the brakepipe locally at a service rate, responsive to the reduction of thepressure in the brake pipe at an emergency rate to cause-the propagationof a pressure impulse hydraulically over another of said passages to theother valve device to cause it to operate to eiect a local reduction ofbrake pipe pressure at an emergency rate and operatively responsive toan increase in pressure in the brake pipe to hydraulically propagate apressure impulse over the third of said passages to the other of saidvalve devices tc cause it to operate to locally supply iiuid underpressure to the brake pipe. f

3, In a car brake equipment of the type having aA brake pipe and a brakecontrolling valve device operatively controlled by variations cipressure in the brake pipe for controlling the brakes on the car; twovalve mechanisms located respectively atopposite ends of the car, meansassociating the two valve mechanisms whereby to cause substantiallyinstantaneous duplicate operationl of one valve device inresponse to theoperation of the other, either of said valve mechanisms being operatedin response to a service reduction of brake pipe pressure to locallyvent fluid under pressure from the brake pipe at a service rate,responsive to an emergency reduction of brake pipe pressure to locallyvent fluid under pressure from the brake pipe at an emergency rate, andresponsive to. an increase'of pressure in the brake pipe for locallysupplying fluid under pressure to the brake pipe. Y

4. In a car brake equipment of the type having a brake pipe` normallycharged with fluid under pressure and a brake controlling valvedeviceoperatively responsive to variations of the pressure in the brakepipe for controlling the brakes on the car; two valve mechanisms locatedrespectively at opposite ends of the car and each having a correspondingchamber therein, means providing a passage connecting the said chambersofthe two valve mechanisms, said chambers and passage being lled with ahydraulic medium, said valve mechanisms each comprising a fluid pressureresponsive element operatively responsive to a reduction of the pressurein the brake pipe for eecting the application of pressure to `thehydraulic medium, valve means operated by `the iiuid pressureresponsive'means for locally kventing uid under pressure from the brakepipe, and additional'valve'means independent of said fluid pressureresponsive means and operated only in response to a pressure impulsehydraulically transmitted thereto for alsolocally venting iluid underpressure from the brake pipe.`

5. In a car brake equipment of the type having a brake pipe normallychargedwith fluid under pressure and a brake controlling valve deviceoperatively responsive to variations of the pressure in the brake pipefor controlling the brakes on the car; the combination of two valveYmechanisms located respectively at opposite ends of thefcar, meansseparate from vthe brake pipe connecting said valve mechanisms forcausingone rvalve mechanism to operate instantaneously in correspondencewith the operation of the other valve mechanism, each of said valvemechanisms comprising a uid pressure responsive means operative inresponse to a service reduction of pressure in the brake pipe forlocally venting iluid under pressure from the brake pipe at a serviceratek and for propagating an impulse over said connecting means to causeduplicate operation of the other valve mechanism, and a second fluidpressure responsive means separate from said rstfluid pressureresponsive means operative in response to an emergency reductio-n ofpressure in the brake pipe for locally Venting fluid under pressure fromthe brake pipe at an emergency rate and for propagating an impulse oversaid connecting means to the other valve mechanism to cause duplicateoperation thereof.

6. In a car brake equipment of the type having a brake pipe normallycharged with fluid under pressure and a brake controlling valve deviceoperatively responsive to variations of the pressure in the brake pipefor controlling the brakes on v the car; the combination of two valvemechanisms located respectively at opposite ends of the car, meansindependent of the brake pipe associating said valve mechanisms so as tocause simultaneous operation of both, each of said valve mechanismshaving a diaphragm subjectto the opposing'pressures of uid supplied tochambers on opposite sides thereof from the brake pipe and having also aquick .service chamber, each diaphragml being operatively responsive toa reduction of brake pipe pressure at a certain rate for effecting alocal'venting of fluid under pressure from the brake pipe to said quickservice chamber and also the operation of the other valve mechanismthrough said associating means, each valve mechanism having also meansoperated in response to Voperation of the other valve mechanism throughsaid associating means for locally venting fluid under pressure from thebrake pipe to its corresponding quick service chamber.

7. In a car brake equipment of the type having a brake pipe normallycharged with uid under pressure and a brake controlling valve deviceoperatively responsive to variations ofthe pressure inthe brake pipe forcontrolling the brakes on the car;'the combination of two valvemechanisms located respectively at opposite endsof the car, hydraulicmeans associating said valve mechanisms, each of saidv valve mechanismshaving a diaphragm subject tothe opposing pressuresof fluidsupplied tochambers on lopposite sides thereof -from the brake pipe and having alsoa quickservice chamber, each diaphragm being operatively responsive to areduction of brake pipey pressure at a certain rate for effecting alocal venting of fluid under pressure from the brake pipe to said quickservice chamber and also the transmission of a pressure impulse over thehydraulic associating means to the other valve mechanism, each valvemechanism having also fluid pressure responsive means subject to apressure impulse received from the other valve mech- Aanism for 'locallyventing fluid under pressure from the brake pipe to its quick servicechamber, leach valve mechanism having also means responsive to arcertainpressure in the quick service vchamber thereof for eiecting a rapidequalization of the pressures in the chambers at opposite sides of saiddiaphragm for causing said diaphragm to return to its normal positionand terminate lthelocal venting of fluid under' pressure from the brakepipe and the transmission of a pressure impulse to the othervalvemechanism. f

l8. `In a car brake equipment of the type having a brake pipe normallycharged with iuid under pressure and a brake controlling valve deviceoperatively responsive to variations of the pressure in the brake pipefor controlling the brakes on the car; the combination of two valvemechanisms locatedrespectively at opposite ends of the car, hydraulicmeans associating said Valve mechanisms, each of said valve mechanismshaving a. diaphragm subject to the opposing pressures of fluid suppliedto chambers on opposite sides Lthereof from the brake pipe and havingalso a quick service chamber, each diaphragm being operativelyresponsive to a reduction of brake pipe pressure at a certain rate foreiecting a local venting of uid under pressure from the brake pipe tosaid quick service chamber and also the transmission of a pressureimpulse over said hydraulic means to the other valve mechanism, eachvalve mechanism having alsofluid pressure responsive means subject to apressure impulse re- .ceived from thev other valve mechanismgfor locallyventing I iuid under pressure from the brake .pipe toits quick servicechamber, each valve ,mechanism having also meansv responsive tof. acertain, pressure in Vthe quick service ,4 chamber thereofl foreITecting rapid equalization of the pressures in the chambers atopposite sides of said diaphragm for causing said diaphragm to return toits normal position and terminate the local venting of uid underpressure from the brake pipe and the transmission of a pressure impulseto the other valve mechanism, and timing means for rendering said lastmeans. nonelective to equalize the pressures in the chambers on oppositesides of said diaphragm after a predetermined time. v .y

9. In a car brake equipment Aof thetype having a brake pipe normallycharged with iuid under pressure and a brake controlling valve deviceop.- eratively responsive to variations of .pressure in the brake pipelfor controlling the brakes on the car; the combination of two valvemechanisms located respectively at opposite ends of the car, said valvemechanisms having corresponding connected chambers lled with a hydraulicmedium and a di-aphragm associated with said chambers forapplyingfpressure to and being subject to the pressure of the hydraulicmedium, each of said valve mechanisms also having means operatively.responsive to a reduction of pressure in the brake pipey for supplyingii'uid under pressure vfrom the brake pipe to act on said diaphragm, andmeans operated in response to the application of hydraulic pressure tothe diaphragm for locally venting fluid under pressure from the brakepipe.

4l0. In a car brake equipment ofthe type having a brake pipe normallycharged with uid under pressure and a brake controlling valve deviceoperatively responsive to variations of pressure in the brake pipe forcontrolling the brakes on the car; the combination of two valvemechanisms:

located respectively at opposite ends of the car,

said valve mechanisms having corresponding chambers hydraulicallyconnected and. also corresponding yother chambers respectively, meansoperatively responsive to the increase of pressure in the brake pipe forlocally supplying uid under pressure fromthe brake pipe to said otherchamber, fluid pressure responsive means subject to the pressure in thesaid other chamber for applying a pressure to the hydraulic mevalve diumin said rst chamber, means operativelycontrolled by the said valve meansfor causing uid under pressure to be supplied locally to the brake pipe,and means responsive to the hydraulic pressure in the first mentionedchamber for also causing fluid under pressure to be locally supplied tothe brake pipe.

l1. In a car brake equipment of the type having a brake pipe normallycharged withfluid under pressure and a brake controlling valve deviceoperatively responsive to variations' of pressure in the brake pipe forcontrolling the brakes on the car; the combination of two valvemechanismsI located respectively at opposite endsof the car, Y

means independent of the brake pipe operatively associating said valvemechanisms to cause sub'- stantially simultaneous duplicate operationthereof, a normally charged reservoir associated with each of said valvemechanisms, each of said valvey mechanisms being operative in responseto an increase of pressure in the brake pipe for supplying uid underpressure from the associated.

reservoir to the brake pipe.

12. In a car brake equipment of the type having a brake pipe normallycharged with uid under pressure and a brake controlling valve device.operatively responsive to variations of pressure" in the brake pipe forcontrolling the brakes on the car;l the combination of two valvemechanisms located respectivelyiatopposite ends of the car, areservoirassociated with each vof said valve mechanisms normallyv charged withfluid under pressure, each of said; valve mechanisms having a valvedevice operative to supplyfluid under pressure from the associatedreservoir to the brake pipe, means operatively responsive tov anincrease of pressure in the brake pipe for eifecting operation of saidvalve device ,to supply fluid under pressure from the said reservoir tothe brakepipe, means operative in response to an increase of pressure inthe brakel pipe for transmitting an impulse independently of the brakepipe to the other valve mechanism, and means operativein response to theimpulse received for also causing operation of said valve device of thecorresponding valve mechanism to supply fluid under pressure from thereservoir tothe brake pipe.

13. In la car brake equipment of the type having a brake pipe normallycharged with fluid under pressure and a brake controlling valve deviceoperatively responsive to variations of pressure in. the brake pipe forycontrolling thebrakes on the car; the combinationof two valve mechanismslocated respectively at opposite ends of the car, a reservoirIassociated with eac-h of -said valve mechanisms, a communicationincluding a one-way valve enabling the charging ofsaid reservoir fromthe brake pipe, each of said valve mechanisms having a valve deviceoperative to cause fluid under pressure to be supplied from saidreservoir to the brake pipe, means operative in response to an increaseof pressurein `the brake pipe for effecting operation of said valvedevice, and means associating said valve mechanisms independently of thebrake pipe for causing operation of the Avalve device of one valvemechanism to vsupply fluid under pressure from the reservoir to thebrake pipe substantially instantaneously upon the operation of the valvedevice off the other valve mechanism to supply fluidrunder pressure fromits associated reservoir to the brake pipe.

14. In a car brake equipment of the type having a brake pipe normallycharged with nuid under pressure and a brake controlling valve deviceoperatively responsive tolvariations of pressure in the brake pipe vforcontrolling the brakes on the car; the combination of a movable abutmentoperatively responsive to an increase of pressure iny the brake pipe, aninshot valve device effective, when operated, to supply a'A limitedamount of fluid under pressure locallyr into the brake pipe, meansoperated in response to the operation of the movable abutment due toanincrease in pressure in the brake pipe for initiating the operationVof the inshot valve means to supply fluid under pressure locally to thebrake pipe, and means effective upon operation of the inshot valvedevice to supply iluid under pressure locally into the brake pipe forconditioning said last meansv to be unresponsive to the operation of themovable abutment in response to a continued increasel of pressure in thebrake pipe for a limited time.

15. In a car brake equipment'of the type having a brake pipe normallycharged with fluid under pressure and a brake .controlling valve deviceoperatively responsivevto variations in pressure in the brake pipefor-controlling the brakes on the car; the combination of a movableabutment subject to the opposing pressures of fluid in chambers atopposite sides thereof, one of which chambers has an unrestrictedcommunication with the brake pipe and the other of which has arestricted communication with the brake pipe whereby upon an increase inpressure` in the brake? pipe saidl abutment is: shifted out of a normalpositiom meansA operated in response to the shifting of the abutment dueto an increase of pressure in the brake pipe for effecting a localsupply of fluid under pressure to the brake pipe, and means for limitingthe degree of differential lbetween .the pressures in thel chambers onopposite sides of said abutment upon an increase of pressure in thebrake pipe. 1 6. In a.- car brake equipment of the type having abrakepipe normally charged with iiuid underpressure-and a brake controllingvalve device operatively responsive to variations of pressure in thebrake pipe for controlling vthe brakes on the car; a valve mechanism;including a flexible diaphragm with chambers on opposite' sides thereof,one of; which chambers has unrestricted -communication With` the brakepipe and the other of which has a constantly open restrictedcommunication Witlr the brake pipe whereby upon an increase ofpressure-in the brake pipe the diaphragm is flexed out of; its normalposition, and

means operated in response to` the flexing ofithev diaphragm as a resultof an increase of brake pipe pressure-for effecting the local supply offluid under pressure to theA brakeY pipe.

17. In a car brake equipment of the type havinga brake pipe normallycharged with fluid under pressure and a brake controlling valve deviceoperatively responsive to variations of pressure in the brake, pipe forcontrolling they brakes on the car; a valve mechanism including aiieXible diaphragm with chambers ,on opposite sides thereof, one ofwhich chambers. has an unrestricted communicationzwith the brake pipeand the other of which hasy a constantly open restricted communicationWith the brake pipe whereby uponan increase of pressure inthe brake pipeit is flexed` out of its normal position, means operated in response tothe flexing of the diaphragm as a. result of an increase inbrake pipepressure for effecting the local supply of fluid under pressurev to thebrake pipe, and a loaded check valvey for limiting the dilferentialofthe pressure in the said one chamber over that inthe said other cham-2ber.

18. In a car'brake equipment of the type having `a brake pipenormallycharged with iluid under pressure and a Vbrake controlling valvedevice operatively responsive tovariations of pressure in the brake pipefor controlling the brakes on the car; a valve mechanism having amovable abutment subject to the Vopposing pressures of Afluid inchambers on oppositesides thereof, one

of' said chambers havingV an unrestricted communication'from the brakepipe and the other chamber having a restricted communication from thebrake pipe,r said abutment being normally in a certain position andshiftable in opposite di-.

rection's out of said position in response to reduction andincrease inthe pressure in the brake pipe at rates exceeding certain uniform rates,

means operated' in response tothe operation of the movable abutment dueto a reduction of pressure in the brake pipe for locally venting fluidunder pressure to the brake pipe, and means operatedfin response to theoperation of the said abutment due to an increase in pressure in thebrake pipe` for-venting fluid under pressure from the .chamber at oneside of said abutment having the restrictedl communication with thebrake pipe whereby to. prevent overcharg'ing of said chamber and aconsequent undesired reapplication of the brakes following a. release ofthe brakes.

1.19,. In a car brake equipment of. the typehavi

